Rudashevsky, N.S., Weiblen, P.W., Stoynov, H., and Saini-Eidukat, B., 1995. Products of electric pulse disaggregation of some Keweenawan rocks, Institute on Lake Superior Geology Proceedings, 41st Annual Meeting, Marathon, Ontario, v. 41, part 1, p. 61.

One of the first publications of EPD approach. With this technology, only from one of the sample from the INCO Spruce Road site (Duluth Complex, Keweenawan), many unknown at that time pristine grains of discrete PGM were observed (recovered) and studied.

Saini-Eidukat, B., Pederson, B., and Weiblen, P.W., 1995. Use of electric pulse disaggregation to liberate fossils from North and South Dakota sediments. North Dakota Academy of Sciences Annual Meeting, Bismarck, ND, April 20-21.

EPD was considered as a novel approach in the fossil liberating. With this method, various types of fossils were succesfully recovered from limestones. The authors proposed that EPD should be considered as a supplement to existing fossil-recovery methods, since it extracts pristine untouched fossils regardless of their size or type.

Saini-Eidukat, B., and Weiblen, P.W., 1996. A new method of fossil preparation, using high-voltage electric pulses. Curator, 39: 139-144.

EPD was successfully used to liberate intact components of fossil-bearing rocks. Even fish scale and microfossils were observed, that could be destroyed by conventional processing. The authors recommended EPD as a routine method for fossil or mineral separation.

T. Meisel, F. Melcher, P. Tomascak, C. Dingeldey, F. Koller Re-Os isotopes in orogenic peridotite massifs in the Eastern Alps, Austria. Chemical Geology 143 (1997) 217-219

Refractory rocks from Eastern Alps, namely chromitites, were successfully disintegtated by EPD. This method can be used to recover individual mineral phases or aggregates even from very hard rocks. Thereby, pristine chromite grains were obtained with further analysis of Re-Os, Sm-Nd and isotope dilution REE concentrations. Based on the authors conclusion, in geochronological studies EPD approach brings valuable information in our understanding of even highly metamorphosed rocks.

N. S. RUDASHEVSKY, А. I. KOSTOYANOV, V. N. RUDASHEVSKY. MINERALOGICAL AND ISOTOPE EVIDENCIES OF ORIGIN OF THE ALPINE-TYPE MASSIFS (BY EXAMPLE OF UST’-BELSKY MASSIF, THE KORYAK HIGHLAND). 1999. Proceedings of the Russian Mineralogical Society. Pt. CXXVIII, № 4.

Hydroseparation provided representative concentrates of PGM, separated from chromitites. With hydroseparation method, it has become possible to conduct qualitative research as well as geochronological and mineralogical studies of PGMs. The obtained data allowed to prove mantle-type and polycyclicity formations of Alpine-type massifs.

Raith, J. & Stein, H. Mineral. Re–Os dating and sulfur isotope composition of molybdenite from tungsten deposits in western Namaqualand, South Africa: implications for ore genesis and the timing of metamorphism Deposita (2000) 35: 741. https://doi.org/10.1007/s001260050276

EPD was succesfully applied for the processing of very soft accessory ores (molybdenite) enclosed in hard matrix (tungsten and quartz) for Re-Os dating analysis. It should be noted that during the processing, boundaries of molybdenite grains were preserved (despite its low hardness). As for the representative homogeneous molybdenite concentrate, measures were taken to process allthe molybdenite from the samples, and EPD was handled it well. A subsequent dating analysis revealed new data on the W-Mo ore formation.

Рудашевский Н.С., Лупал С.Д., Рудашевский В.Н. Гидравлический классификатор. Патент на изобретение №2165300. РФ. М. 2001.

N. S. Rudashevsky, G. Garuti, J. C. Ø. Andersen, Yu. L. Kretser, V. N. Rudashevsky & F. Zaccarini (2013) Separation of accessory minerals from rocks and ores by hydroseparation (HS) technology: method and application to CHR-2 chromitite, Niquelândia intrusion, Brazil, Applied Earth Science, 111:1, 87-94, DOI: 10.1179/aes.2002.111.1.87

The hydroseparator embodies novel technology that can be of great benefit for the study of accessory minerals in rocks, ores, industrial products and materials of potential environmental concern. The technique is described and an example is provided of its application in the study of the platinum-bearing CHR-2 chromitite of the Niquelândia layered intrusion, central Goiás, Brazil.

Garuti G. et al. Platinum-group element mineralization in chromitites of the Niquelândia layered intrusion (central Goiás,Brazil): new findings by the use of the hydroseparation (HS) technology. In Proc. 9th Int. platinum symposium, Billings, Montana, 2002 (inpress).

The use of hydroseparation (HS) has provided new observations in the chromitites of the Niquelandia layered intrusion (Central Goias, Brazil). With HS technology, the presence of relatively coarse grains (up to 100 µm) of Pt-Fe alloys, which were previously missed in the study of polished sections, was discovered. In addition, more than 12 minerals were observed in the Niquelandia chromitites, which have never been described before. HS allowed to review Niquelandia chromitite-PGE mineralization and assume its origin by mixing two magmas at different stages of differentiation.

LASTRA R., CABRI L., WEIBLEN P., 2003. Comparative Liberation study by image analysis of Merensky Reef samples comminuted by electric-pulse disaggregation and by conventional crusher, Proceeding of XXII International Mineral Processing Congress, Cape Town, South Africa,1, 251-260

Preliminary tests were done to determine whether comminution by electric-pulse disaggregation, or E-PD (cf. Rudashevsky et al; 1995), was more effective than using conventional crushing for Merensky Reef ore. A hand sample of the Merensky Reef was sawn in two: then one sub-sample was comminuted to ñ2 mm using E-PD at the University of Minnesota, and the other sub-sample was crushed to ñ2 mm using a conventional jaw crusher at CANMET. The products of the electric-pulse disaggregation and jaw crusher were fractionated by sieving and by a separation using a heavy liquid with a specific gravity of 3.3, because the proportion of platinum-group minerals (PGM) and sulphides to silicate minerals is very low. Thus, four mineral separates were produced: ñ2000 + 833 μm, -833 +208 μm, -208-μm float and -208-μm sink. All the mineral separates were studied by image analysis (Lastra et al; 1998). The main objective was to determine the liberation of gangue (silicate minerals), chromite, pyrrhotite, chalcopyrite, pentlandite and PGM. In the case of the PGM, a specific image analysis program was written to search and measure these minerals. The results show that the liberation obtained for gangue was similar (~99%) using either method of comminution. However, the liberation obtained for chromite (~89% vs. ~38%), pentlandite (~50% vs. 1%), pyrrhotite (~56% vs. ~38%), and PGM (~56% vs. ~1%) by E-PD was higher than that obtained by conventional jaw crusher, whereas the liberation obtained for chalcopyrite (~20% vs. ~71%) by E-PD was lower. Nevertheless, the image analysis of the products also showed that the PGM are strongly associated with pentlandite. Thus, for the Merensky Reef, liberation of pentlandite from the gangue minerals and chromite is important to recover more of the PGM. This maybe be significant because, in addition to increased recovery of platinum-group minerals (PGM), Merensky Reef pentlandite also contains significant quantities of valuable platinum-group elements like Pd and Rh (Cabri, 1981; Cabri 1988, Kinloch 1982, Peyerl 1983). Hence, the results indicate that for the Merensky Reef, electric-pulse disaggregation would represent a better comminution operation than a conventional jaw crusher would. In addition, the greatly improved liberation for chromite may find application for the PGM-rich UG2 chromitite.

Oberthür, T., Weiser, T.W., Gast, L. et al. (2003) Geochemistry and mineralogy of platinum-group elements at Hartley Platinum Mine, Zimbabwe. Miner Deposita 38: 327. https://doi.org/10.1007/s00126-002-0337-9

The Main Sulfide Zone (MSZ) is the most prominent layer of the Great Dyke layered intrusion carrying economic platinum-group element (PGE) min-eralization. At the Hartley Platinum Mine, the MSZ is up to some meters thick and is composed of a basal PGE-rich subzone which overlaps slightly with a base metal, sulfide-rich subzone on top. Based on the degree of sulfide mineralization and PGE ratios, the subzones can be further divided into geochemically distinct layers. Stratigraphically upwards, the MSZ displays metal profiles characterized by increasing Cu/Ni, Pt/Pd and PPGE/IPGE ratios, accompanied by a general element decoupling in the order Pd fi Pt fi base metals, more specifically IPGE fi Pd fi Pt fi (Ni,Cu,Co,S (sulfides), Au,Te,Bi. The fine structure of the MSZ is regarded to reflect primary magmatic features of consecutive batches of sulfide accumulation, concomitant scavenging of PGE, and fractionation. Sulfide deposition was followed by a second, limited subsolidus stage of PGE redistri-bution. Mineralogically, most of the Pd and Rh is hosted in pentlandite, whereas Pt is dominantly present in the form of discrete platinum-group minerals (PGM). Within the MSZ sequence, sperrylite is present throughout the PGE subzone of the MSZ, cooperite/braggite occur mainly in its basal part, and the (Pt,Pd)-bismuthotellurides concentrate at the top. These findings indicate that a large proportion of the PGE, primarily concentrated in sulfide under magmatic conditions, was redistributed in the subsolidus stage and formed discrete PGM with available reactant partners. Chemical gradi-ents and magmatic–hydrothermal fluids probably led to small-scale redistribution of PGE within the MSZ.

John W. Valley Oxygen Isotopes in Zircon. Reviews in Mineralogy and Geochemistry Jan 2003, 53 (1) 343-385; DOI: 10.2113/0530343

An example of using EPD to recover monomineral fractions followed by isotopic analysis was showed. Due this approach the 4.33 Ga zircon core was found, instead of losing such one using conventional crushing. The Author recommends EPD method for oxygen isotope analysis in Zircon, as this technique can preserve delicate features in igneous, metamorphic or sedimentary rocks.

Johann G. Raith, David H. Cornell, Hartwig E. Frimmel, and Coenraad H. De Beer New Insights into the Geology of the Namaqua Tectonic Province, South Africa, from Ion Probe Dating of Detritaland Metamorphic Zircon The Journal of Geology, 2003, volume 111, p. 347–366

An ion microprobe study in the western part of the Namaqua-Natal Tectonic Province of South Africa provides new insights into ages of sedimentation, magmatism, and metamorphism in the Bushmanland Terrane. Concordant U-Pb ages and discordia regressions are reported for three samples and, in combination with secondary electron microscope images, Th/U ratios, and rare earth element analyses of different zircon age domains, are used to distinguish several igneous and metamorphic events. Detrital zircon grains from the tectono-stratigraphic lowermost part of the Ka-miesberg Subgroup (Louisrus Formation) yielded ages between 1200 and 1250 Ma and formed before a first tectono-thermal event at 1187 Ma. In contrast, detrital zircon grains from a metapelitic granulite from the top of the subgroup (Bitterfontein Formation) were deposited during a previously unrecognized sedimentation stage after 1157 Ma and after this first tectono-thermal event. Therefore, at least parts of the supracrustal rocks in the Bushmanland Terrane are derived from 1250–1200 Ma crustal material and are not Paleo- to Mesoproterozoic, as suggested previously. Two major magmatic episodes have previously been recognized: at ∼1.2 Ga (Little Namaqualand Suite) and at 1.03–1.06 Ga (Spektakel and Koperberg Suites). In addition, we have dated another episode of bimodal felsic (Landplaas) and mafic (Oorkraal) plutonism at Ma. With respect to the metamorphic history, we directly date a stage 1109 20/ 19 of early Namaqua metamorphism at Ma that had previously only been envisaged to accompany 1187 15 ∼1.2 Ga plutonism. We also confirm the age and regional significance of the second low-pressure, high-temperature granulite facies metamorphic event at 1.02–1.03 Ga and the effects of the low-grade Pan-African overprint at ∼0.5 Ga.

K.N. Malitch, F. Zaccarini, G. Garuti Preliminary results of the "in situ" investigation of platinum-group minerals in chromitites from the Kondyor and Guli ultramafic massifs (Russia). Mineral Exploration and Sustainable Development. Millpress, Rotterdam, Netherlands, 611-614

The Kondyor and Guli clinopyroxenite-dunite complexes (Siberian Craton) contain small bodies of schlieren to massive chromitite associated with dunite. The “in situ” investigation of the platinum-group minerals (PGM) from the chromitite of the Kondyor complex matches well the whole-rock platinum-group elements (PGE) geochemistry and mineralogical data of PGM nuggets from the placers. The in situ PGM observed in chromitite at Guli fit the whole-rock PGE pattern, but only partially match PGE mineralogy reported from the nuggets. Therefore, the great importance of the chromitites related with clinopyroxenite-dunite complexes as primary source of PGM is confirmed at Kondyor, whereas at Guli the chromitites along with other source-rocks, which are not yet identified, are assumed to be the primary source for detrital noble metal mineralization.

Nielsen T.F.D., Rasmussen H., Rudashevsky N.S., Kretzer Y.L., Rudashevsky V.N. PGE and sulphide phases of the precious metal mineralisation of the Skaergaard intrusion, Part 1: sample 90-23A, 807. Geological Survey of Denmark and Greenland, Ministri of the Environment. (GEUS). Report 2003/47. 2003a. 11 pp.

This is one of several mineralogical reports on the noble mineralization of the Skaergaard. From one sample (0,76 kg) 165 precious metal grains were found, due the concentration using hydroseparator. 15 different species of precious metal minerals and phases have been identified in the investigated sample. The whole-rock Pd:Au:Pt ratio based on a balance between the phases is very close to the assay ratio.

Nielsen T.F.D., Rasmussen H., Rudashevsky N.S., Kretzer Y.L., Rudashevsky V.N. (2003b). PGE and sulphide phases of the precious metal mineralisation of the Skaergaard intrusion, Part 2: sample 90-24, 1057. Geological Survey of Denmark and Greenland, Ministri of the Environment. (GEUS). Report 2003/48. 2003b. 83 pp.

This is one of several mineralogical reports on the noble mineralization of the Skaergaard. 374 grains of PGM were concentrated from 1 sample (0,78 kg) by HS technology. Several unnamed mineral phases were found, including future-named Skaergaardite, which represents totally dominating PGM.

Nielsen T.F.D., Rasmussen H., Rudashevsky N.S., Kretzer Y.L., Rudashevsky V.N. PGE and sulphide phases of the precious metal mineralisation of the Skaergaard intrusion, Part 3: sample 90-18, 1010. Geological Survey of Denmark and Greenland, Ministri of the Environment. (GEUS). Report 2003/52. 2003c. 67 pp.

This is one of several mineralogical reports on the noble mineralization of the Skaergaard. 180 grains of PGM and 17 mineral species were concentrated from 1 sample (0,8 kg) by HS technology. Compared to the assay the Pd concentration and the total (Pd+Au+Pf) is reproduced in the mass balance calculation.

Nielsen T.F.D., Rasmussen H., Rudashevsky N.S., Kretser Yu.L., Rudashevsky V.N. PGE and sulphide phases of the precious metal mineralisation of the Skaergaard intrusion. Part 4: sample 90-23A, 806 // Geological Survey of Denmark and Greenland, Ministry of the environment (GEUS) / Report 2003/ 53. 2003d 41 p.

This is one of several mineralogical reports on the noble mineralization of the Skaergaard. 50 grains of PGM and 36 grains of Au- and Ag-minerals were concentrated from 1 sample (average PGE+Au content 2,0g/t) by HS technology.

Nielsen T.F.D., Rasmussen H., Rudashevsky N.S., Kretzer Y.L., Rudashevsky V.N. (2003e). PGE and sulphide phases of the precious metal mineralisation of the Skaergaard intrusion, Part 5: sample 90-23a, 808. Geological Survey of Denmark and Greenland, Ministri of the Environment. (GEUS). Report 2003/54. 2003e. 37 pp.

This is one of several mineralogical reports on the noble mineralization of the Skaergaard. The HS-concentrates of sample yielded 112 grains of PGMs and 3 grains of Au-minerals. The grain size varies from 2 to 69 μm with average 15 μm. The recovery of Au-minerals demonstrates the sensivity of the HS-concentrator with presumably <0,1 ppm sensitivity of the HS-technology for PGMs and Au-minerals.

Rudashevsky, N.S., Kretser, Y.L., Rudashevsky, V.N. and Sukharzhevskaya, E.S. (2004) A review and comparison of PGE, noble-metal and sulphide mineralization in phoscorites and carbonatites from Kovdor and Phalaborwa. In Phoscorites and Carbonatites from Mantle to Mine: the Key Example of the Kola Peninsula Alkaline Province (Wall, F. and Zaitsev, A.N. Eds.). Mineralogical Society, London, 375-406.

Comparative characteristics of PGE, noble-metal and sulphide mineralization inphoscorites and carbonatites from the Kovdor and Phalaborwa deposits are given. Four typical sulphide-rich samples from Kovdor and Phalaborwa (phoscorites and carbonatites from both deposits, as well as sulphide concentrate from the Kovdor Concentrating Mill and a flotation sulphide concentrate from the Palabora Mining Company) were studied. In Kovdor, mainly in calcite-richareas of the phoscorites, small, drop-shaped isolated sulphide (pyrrhotite, chalcopyrite 3 pentlandite) inclusions occur in calcite, as well as similar calcite inclusions in sulphide aggregates. Besides these and other rare sulphides, six Pt-bearing minerals, nine Pd-bearing minerals and four Au minerals were identified in the ‘heavy concentrates’ of the Kovdor samples. Copper-bearing minerals – bornite, chalcopyrite, minerals of the chalcosine group and cubanite – dominate within sulphides of the samples from the Loolekop deposit, Phalaborwa. Typical exsolution textures of chalcopyrite– bornite solid solution, as well as myrmekitic intergrowths of bornite and chalcosine-group minerals are usually observed. Besides these sulphides and other scarcer ore minerals, one Pt-bearing mineral, eight Pd minerals, four Au-bearing minerals, and five Ag-bearing minerals were identified in the ‘heavy concentrates’ of the Phalaborwa samples.

L.J. Cabri (2004) New developments in Process Mineralogy of Platinum-bearing Ores. Proceedings of the Canadian Mineral Processors, 36th Annual Meeting, Ottawa, 189-198.

Mineralogical evaluation of ores containing platinum-group elements (PGE) is fraught with difficulties because of the low grades (often 1-3 g/t PGE), dispersal of PGE (usually as fine-grained platinum-group minerals [PGM]), as well as occurring in solid solution in some base metal sulphides (BMS) such as pentlandite and pyrrhotite. Mineral processors not only need to know how the PGE are distributed, that is, their mineralogical distribution, but the grain sizes of the PGM, and especially the associated minerals. After obtaining a representative ground sample, common approaches include studying a large number of polished or polished thin sections, concentration of the PGM and sulphides by different gravity methods (e.g., heavy liquids, elutriation, micro-panning) and study of the produced concentrates. Unfortunately, these methods often do not produce concentrations that are sufficiently representative of a particular ore. The newly developed patented technology of hydroseparation (Rudashevsky et al., 2002) is especially effective at making concentrations of PGM over a wide range of concentrations (down to <300 ppb Pt+Pd+Au) and size fractions, including <45μm (down to a few micrometres in size), a size range not possible by other techniques. This water-based environmentally friendly laboratory technique provides a large amount of data from samples, which can range from 5 to 1000g, giving confidence to extrapolation of results to bench-scale and larger test work, especially when combined with quantitative image analysis to determine modal percent of major minerals and mineral liberation data, needed to predict the minimum (K80) and optimum (K40) grinds.

Rudashevsky NS, McDonald AM, Cabri LJ, Nielsen TFD, Stanley CJ,Kretzer YL, Rudashevsky VN (2004) Skaergaardite, PdCu, a newplatinum-group intermetallic mineral from the Skaergaard intrusion,Greenland. Miner Magaz 68:615–632 DOI: 10.1180/0026461046840208

Skaergaardite, PdCu, is a new mineral discovered in the Skaergaard intrusion, Kangerdlugssuaq area, East Greenland. It occurs in a tholeitiic gabbro associated with plagioclase, clinopyroxene, orthopyroxene, ilmenite, titanian magnetite, fayalite and accessory chlorite-group minerals, ferrosapo-nite, a member of the annite–phlogopite series, hornblende, actinolite, epidote, calcite, ankerite, apatite and baddeleyite. The mineral is found in composite microglobules composed of bornite, chalcocite, digenite, chalcopyrite, with rare cobalt pentlandite, cobaltoan pentlandite, sphalerite, keithconnite, vasilite, zvyagintsevite, (Cu,Pd,Au) and Pt-Fe-Cu-Pd alloys, unnamed PdCu3, (Pd,Cu,Sn), Au3Cu and PdAuCu. Skaergaardite occurs as droplets, equant grains with rounded outlines, subhedral to euhedral crystals and as irregular grains that vary in size from 2 to 75 mm, averaging 22 mm. It is steel grey with a bronze tint, has a black streak, a metallic lustre and is sectile. Neither cleavage nor fracture was observed. The mineral has a micro-indentation hardness of VHN25 = 257. It is isotropic, non-pleochroic and exhibits neither discernible internal reflections nor evidence of twinning. Skaergaardite varies from bright creamy white (associated with bornite and chalcopyrite) to bright white (associated with digenite and chalcocite). Reflectance values in air (and in oil) are: 58.65 (47.4) at 470 nm, 62.6 (51.1) at 546 nm, 64.1 (52.8) at 589 nm and 65.25 (53.95) at 650 nm. The average of 311 electron-microprobe analyses gives: Pd 58.94, Pt 1.12, Au 2.23, Cu 29.84, Fe 3.85, Zn 1.46, Sn 1.08, Te 0.28 and Pb 0.39, total 99.19 wt.%, corresponding to (Pd0.967A u0.020Pt 0.010 )S0.997 (Cu0.820F e 0.120 Zn0.039Sn0.016Te0.004Pb0.003)S1.002. The mineral is cubic, space group Pm3m, a = 3.0014(2) A ̊ , V = 27.0378 A ̊ 3, Z = 1. Dcalc is 10.64 g/cm3. The six strongest lines in the X-ray powder-diffraction pattern [d inA ̊ (I)(hkl)] are: 2.122(100)(110), 1.5000(20)(200), 1.2254(50)(211), 0.9491(20)(310), 0.8666(10)(222), 0.8021(70)(321). The mineral has the CsCl-type structure. It is believed to be isostructural with wairauite (CoFe), synthetic CuZn (b-brass) and is structurally related to hongshiite (PtCu). Skaergaardite developed from a disordered Pd-Cu-rich metal alloy melt that had exsolved from an earlier Cu-(Fe) sulphide melt. Ordering of Pd and Cu (beginning at T & 600oC) results in development of the CsCl structure from a disordered face-centred cubic structure.

Raith, J.G., Riemer, née Schöner, N. & Meisel, T. Boron metasomatism and behaviour of rare earth elements during formation of tourmaline rocks in the eastern Arunta Inlier, central Australia. Contrib Mineral Petrol (2004) 147: 91. https://doi.org/10.1007/s00410-003-0548-9

Tourmaline rocks of previously unclear genesis and spatially associated with W- (Cu)-bearing calc-sili-cate rocks occur in Palaeoproterozoic supracrustal and felsic intrusive rocks in the Bonya Hills in the east-ern Arunta Inlier, central Australia. Tourmalinisation of metapelitic host rocks postdates the peak of regional low-pressure metamorphism (M1/D1, 500 C, 0.2 GPa), and occurred synkinematically between the two main deformation events D1 and D2, coeval with emplacement of Late Strangways (1.73 Ga) tourma-line-bearing leucogranites and pegmatites. Tourmaline is classified as schorl to dravite in tourmaline–quartz rocks and surrounding tourmaline-rich alteration zones, and as Fe-rich schorl to foitite in the leucogranites. Boron metasomatism resulted in systematic depletion of K, Li, Rb, Cs, Mn and enrichment of B, and in some samples of Na and Ca, in the tourmaline rocks compared to unaltered metasedimentary host rocks. Whole-rock REE concentrations and patterns of unaltered schist, tourmalinised schist and tourmaline–quartz veins—the latter were the zones of influx of the boron-rich hydro-thermal fluid—are comparable to those of post-Ar-chaean shales. Thus, the whole-rock REE patterns of these rocks are mostly controlled by the metapelitic precursor. In contrast, REE concentrations of leuco-granitic rocks are low ( £ 10 times chondritic), and their flat REE patterns with pronounced negative Eu anomalies are typical for fractionated granitic melts coexisting with a fluid phase. REE patterns for tourmalines separated from metapelite-hosted tourmaline–quartz veins and tourmaline-bearing granites are very different from one another but each tourmaline pattern mirrors the REE distribution of its immediate host rock. Tourmalines occurring in tourmaline–quartz veins within tour-malinised metasediments have LREE-enriched (LaN/YbN=6.3–55), shale-like patterns with higher SREE (54–108 ppm). In contrast, those formed in evolved leucogranites exhibit flat REE patterns (LaN/YbN=1.0–5.6) with pronounced negative Eu anomalies and are lower in SREE (5.6–30 ppm). We therefore conclude that REE concentrations and patterns of tourmaline from the different tourmaline rocks studied are controlled by the host rock and not by the hydrothermal fluid causing boron metasomatism. From the similarity of the REE pattern of separated tourmaline with the host rock, we further conclude that incorporation of REEs in tourmaline is not intrinsically controlled (i.e. by crystal chemical factors). Tourmaline does not prefer- entially fractionate specific REEs or groups of REEs during crystallisation from evolved boron- and fluid-rich granitic melts or during alteration of clastic metasediments by boron-rich magmatic-hydrothermal fluids.

Langthaler, K., Raith, J., Cornell, D. et al. Molybdenum mineralization at Alpeiner Scharte, Tyrol (Austria): results of in-situ U–Pb zircon and Re–Os molybdenite dating. Mineralogy and Petrology (2004) 82: 33. https://doi.org/10.1007/s00710-004-0048-2

Vein-type Mo mineralization at Alpeiner Scharte occurs in the Penninic units of the western Tauern Window in the Eastern Alps. Three types of previously undated meta-granitoids (central gneisses) are distinguished and preserve intrusive contacts with pre-Alpine metamorphosed supracrustal rocks. The granitic protoliths represent fractionated late to post-orogenic, calc-alkaline, I-type magmas with minor S-type components. The Mo veins are restricted to a biotite and alkali feldspar-rich gneiss variety and occur in E–W trending normally sub-vertical quartz veins with adjacent thin discontinuous garnet-and biotite-rich zones; the latter are interpreted as metamorphosed vein selvages. Prior to this work the age of the intrusive host rocks as well as the age of Mo mineralization were unknown. The pre-Alpine Mo deposit and its host rocks were affected by four Alpine de-formation events (D1–D4) and Young-Alpine regional metamorphism. The P-T conditions of this metamorphic event were 550 C and 8 kbar and are in agreement with results of previous regional studies. Zircon grains from two orthogneiss samples were dated with the U–Pb method using ion probe techniques. Zircons from the metagranitic host rock of the Mo-veins yielded an emplacement age of 306.8 3.8 Ma (2). A second sample from a more leucocratic gneiss lacking Mo-veins gave 305.0 6.6 Ma (2). Re–Os dating of molybdenite from the veins yielded an age of 306.8 3.1 Ma, in good agreement with the U–Pb zircon ages. This study confirms one of two alternative hypotheses discussed in the literature. It supports the idea that vein-type Mo-mineralization in the western Tauern Window is genetically related to Late Carboniferous (Westphalian) granitoids that were emplaced during the late to post-orogenic stage of the Variscan orogeny. They do not constitute an Alpine metamorphic-hydrothermal deposit. This study further confirms the strength of the Re–Os molybdenite chronometer, in that it was unaffected by subsequent Alpine medium grade regional metamorphism.

Aaron J. Cavosie, Simon A. Wilde, Dunyi Liu, Paul W. Weiblen, John W. Valley, Internal zoning and U–Th–Pb chemistry of Jack Hills detrital zircons: a mineral record of early Archean to Mesoproterozoic (4348–1576Ma) magmatism, In Precambrian Research, Volume 135, Issue 4, 2004, Pages 251-279, ISSN 0301-9268, https://doi.org/10.1016/j.precamres.2004.09.001

Magmatic processes were important on the nascent Earth during the first 500 million years (Ma) after accretion, yet the causes and timing of this early magmatism are largely unconstrained, as no rocks from this period have been discovered. Rare >4000 Ma detrital zircons from Western Australia preserve the only direct geologic evidence of this early magmatism. To understand the genesis and history of these zircons, we present the results of a combined ion and electron microprobe, and SEM study of the age, Th–U chemistry, cathodoluminescence (CL) zoning patterns, and inclusions for a population of detrital zircons from Jack Hills, Western Australia, with 207Pb/206Pb ages ranging from 4348 to 1576 Ma. The majority of the zircons preserve primary growth features discernable by CL imaging, such as oscillatory and sector zoning, have Th/U ratios from 0.1 to 1.0, and several contain granitic mineral inclusions. Thus, aside from age they are largely indistinguishable from zircons produced in common felsic magmas. The Jack Hills zircons are therefore remnants of igneous rock-forming events that pre-date the rock record by up to 400 Ma. The 207Pb/206Pb age distribution pattern for zircons older than 3800 Ma from Western Australia suggests that early Archean magmatism was punctuated, both in terms of high frequency events and conspicuous gaps. The variable age distributions within different rock units in the Jack Hills demonstrate that Early Archean zircons were derived from multiple source rocks; samples from Eranondoo Hill contain up to 12% >4000 Ma zircons, suggesting either that the source rocks were nearby or represent a large terrane. Furthermore, younger 3700–3400 Ma rims on 4300–4000 Ma zircons are evidence that >4000 Ma crust survived long enough to participate in younger Archean tectonic events in the Yilgarn Craton of Western Australia. Mesoproterozoic igneous zircons in a quartzite 50 m from Eranondoo Hill are attributed to either sedimentation or tectonic interleaving of younger sediments no earlier than 1576 Ma. This previously unrecognized Proterozoic (or younger) geologic history calls into question previous estimates of the age of the Jack Hills sediments and demonstrates the heterogeneous distribution of >4000 Ma grains within the belt.

Lastra, R., Price, J., Cabri, L. J., Rudashevsky, N. S., Rudashevsky,V. N. and McMahon, G. 2005. Gold characterisation of a samplefrom Malartic East (Quebec) using concentration by hydroseparator, in Treatment of gold ores – 5th InternationalSymposium, 44th Annual Conference of Metallurgists of CIM,(ed. G. Descheˆneset al.); Calgary, Alta, MetSoc, 711–715.

A gold sample assaying 11.4 g Au/t was selected for this study. Approximately 99% of the gold in this sample occurs as discrete gold minerals; the balance occurring as invisible gold in pyrite (determined by SIMS analysis). The sample was coarsely ground and sieved, yielding ~38, 17, 22 and 22 wt.% in the -400+160 um, -160+80 um, -80+40 um and -40 um size fractions. Assays of the size fractions gave a gold distribution of ~32, 20, 21, and 27% respectively. Processing with the hydroseparator (model HS-02) gave two tailings products and one concentrate from each size fraction. Assays of the concentrate from each size fraction gave gold recoveries of ~7, 7, 24, 19%, respectively. Polished sections were prepared from each hydroseparation product and studied by image analysis to automatically search for gold minerals. Calculations were using the surface area of the grains of gold minerals found on the polished sections. Using only information from the concentrates, it was determined that ~78% of the gold is free, compared to ~66% free gold in the combined tailings plus concentrate. The calculated distribution of the gold minerals was ~79% electrum, 11% gold tellurides, and ~10% native gold in the concentrates comparing closely with ~79% electrum, ~13% gold tellurides, and ~8% native gold in the combined tailings plus concentrate. The calculated grain size distribution of the gold minerals showed that in the concentrates ~78% of the gold is between 26 and 74 um compared to ~61% of the gold between 26 and 74 um for the combined tailings plus concentrates. Thus, the characterization of the gold minerals derived from the concentrates is similar to the one derived for the reconstructed sample. The total area of gold grains found in the four polished sections of the concentrates is ~22,219 um', which is 10 times that found in 10 polished sections of un-ground and unprocessed sample. These results clearly indicate the benefits of pre-concentration for gold characterization. Though the tests showed that hydroseparation did not concentrate all the gold, it yielded rich concentrates representative of the ore, which does simplify the mineralogical gold characterization.

CABRI, L.J., MCDONALD, A.M., STANLEY, C.J., RUDASHEVSKY, N.S., POIRIER, G., DURHAM, B.R., MUNGALL, J.E. & RUDASHEVSKY, V.N. (2005): Naldrettite, Pd2Sb, a new intermetallic mineral from the Mesamax Northwest deposit, Ungava region, Quebec, Canada. Mineral. Mag. 69, 89-98. DOI: 10.1180/0026461056910236

Naldrettite, Pd2Sb, is a new intermetallic mineral discovered in the Mesamax Northwest deposit, Cape Smith fold belt, Ungava region, northern QueÂbec. It is associated with monoclinic pyrrhotite, pentlandite, chalcopyrite, galena, sphalerite, cobaltite, clinochlore, magnetite, sudburyite (PdSb), electrum and altaite. Other rarer associated minerals include a second new mineral (ungavaite, Pd4Sb3), sperrylite (PtAs2), michenerite (PdBiTe), petzite (Ag3AuTe4) and hessite (Ag2Te). Naldrettite occurs as anhedral grains, which are commonly attached or moulded to sulphide minerals, and also associated with clinochlore. Grains of naldrettite vary in size (equivalent circle diameter) from ~10 to 239 mm, with an average of 74.4 mm (n = 632). Cleavage was not observed and fracture is irregular. The mineral has a mean micro-indentation hardness of 393 kg/mm2. It is distinctly anisotropic, non-pleochroic, has weak bireflectance, and does not exhibit discernible internal reflections. Some grains display evidence of strain-induced polysynthetic twinning. Naldrettite appears bright creamy white in association with pentlandite, pyrrhotite, clinochlore and chalcopyrite. Reflectance values in air (and in oil) for R1 and R2 are: 49.0, 50.9 (35.9, 37.6) at 470 nm, 53.2, 55.1 (40.3, 42.1) at 546 nm, 55.4, 57.5 (42.5, 44.3) at 589 nm and 58.5, 60.1 (45.4, 47.2) at 650 nm. The average of 69 electron-microprobe analyses on 19 particles gives: Pd 63.49, Fe 0.11, Sb 35.75, As 0.31, and S 0.02, total 99.68 wt.%, corresponding to (Pd1.995Fe0.007)2.002(Sb0.982As0.014S0.002)0.998. The mineral is orthorhombic, space group Cmc21, a 3.3906(1), b 17.5551(5), c 6.957(2) AÊ , V 414.097(3) AÊ 3, Z = 8. Dcalc is 10.694(1) g/cm3. The six strongest lines in the X-ray powder-diffraction pattern [d in AÊ (I)(hkl)] are: 2.2454(100)(132), 2.0567(52)(043), 2.0009(40)(152), 1.2842(42)(115), 1.2122(50)(204) and 0.8584(56)(1.17.4).

Cabri, L.J., Beattie, M., Rudashevsky, N.S., et al., Process mineralogy of Au, Pd and Pt ores from the Skaergaard intrusion, Greenland, using new technology, Miner. Eng., 2005, vol. 18, pp. 887–897. DOI: 10.1016/j.mineng.2005.01.021

Hydroseparation (HS) was applied to study two samples from the Skaergaard instrusion, Greenland. About 500 pristine grains of precious metal minerals (PMM) was recovered from each sample. The obtained data allowed to determine the nature of PMM and provide guidance for mineral processing. HS enabled to perform a rapid analysis on a large number of Au and PGM grains, instead of conventional polished section approach. Authors recommend using HS for its statistical relevance.

McDonald, A.M., Cabri, L.J., Stanley, C.J., Rudashevsky, N.S., Poirier, G., Mungall, J.E., Ross, K.C., Durham, B.R., and Rudashevsky, V.N. (2005) Ungavaite, Pd4Sb3, a new intermetallic mineral species from the Mesamax northwest deposit, Ungava Region, Quebec, Canada: description and genetic implications. The Canadian Mineralogist, 43, 1735–1744. DOI: 10.2113/gscanmin.43.5.1735

Ungavaite, Pd4Sb3, is a new intermetallic mineral species discovered in the Mesamax Northwest deposit, Cape Smith fold belt, Ungava region, northern Quebec. It is associated with monoclinic pyrrhotite, pentlandite, chalcopyrite, galena, sphalerite, cobaltite, a chlorite-group mineral and magnetite. Associated precious-metal minerals include another new mineral species, naldrettite (Pd2Sb), sperrylite, sudburyite, michenerite, Au–Ag alloy, altaite, petzite (Ag3AuTe4) and hessite (Ag2Te). Ungavaite occurs as rare anhedral grains with inclusions of Au–Ag alloy or with attached chalcopyrite and a chlorite-group mineral. Grains of ungavaite vary in size (equivalent circle diameter) from ca. 36 to 116 m, with an average of 73 m (n = 4). Neither cleavage nor fracture was observed. It is distinctly anisotropic, non-pleochroic, has weak birefl ectance and does not exhibit discernible internal refl ections. Ungavaite appears bright creamy white in association with pentlandite, pyrrhotite, the chlorite-group mineral and chalcopyrite. Refl ectance values in air (and in oil) for R1 and R2 are: 50.2, 50.5 (37.6, 38.0) at 470 nm, 55.6, 55.9 (43.2, 43.5) at 546 nm, 57.9, 58.3 (45.9, 46.3) at 589 nm and 60.2, 60.7 (48.1, 48.5) at 650 nm. The average result of 16 electron- microprobe analyses on one particle is: Pd 54.53, Fe 0.13, Te 0.09, Sb 44.59, Bi 0.42, Hg 0.19, and As 0.20, total 100.15 wt. %, corresponding to empirical formula (based on seven atoms) Pd4.062(Sb2.893Fe0.017Bi0.017Hg0.006Te0.005)2.938, ideally Pd4Sb3. The mineral is the Pd-dominant analogue of genkinite. It is tetragonal, crystallizing in one of the possible space-groups P41212, P4122, P43212, P42212, or P4222. Cell dimensions are: a 7.7388 (4), c 24.145(1) Å, with V = 1446.02(1) Å3 and Z = 8. The calculated density is 7.264(1) g/cm3 . The strongest six lines in the X-ray powder-diffraction pattern [d in Å(I)(hkl)] are: 3.008(90)(008), 2.268(100)(134), 2.147(30)(230), 1.9404(60)(400), 1.2043(30)(2218, 452), 1.2002(30)(624). The mineral formed in a narrow (Pd + Sb)-rich zone separating massive and disseminated sulfi des. It is likely a product of the hydrothermal remobilization of Pd (and possibly Sb) from the pre-existing massive sulfi des. Phase relations suggest that ungavaite developed at a temperature below 400°C, possibly through a solid-state order–disorder transformation.

Cabri L.J. et al. Current developments in quantitative process mineralogy of PGE-bearing ores from different deposits. 10th International Platinum Symposium “Platinum-Group Elements – from Genesis to Beneficiation and Environmental Impact”, Oulu, Finland, 8-11 August, 2005

Improvements to techniques and methodology used in the process mineralogy of platinum-group element (PGE)-bearing samples have focused on improvements to quantify all determinations in order to make the data more useful for process engineers and metallurgists. The study of heavy accessory minerals such as platinum-group minerals (PGM) in rocks, ores, and processed products is usually limited by the scarcity and small grain size of the target minerals. However, for quantitative process mineralogy of PGE-bearing samples one has to employ an appropriate combination of physical and microanalytical approaches that are tailored for the sample type and grade. The hydroseparation technique (HS) has proved to be very effective at concentrating a representative proportion of PGM and associated minerals in different sample types. Recent developments in microbeam analyses indicates that the laser ablation microprobe – inductively coupled plasma – mass spectrometry (LAM-ICP-MS) can provide multi-PGE analyses of PGE-bearing sulfides at detection levels of 10s of ppb. It can be used in combination with electron probe microanalyses (EPMA) for minor and major elements and with quantitative image analysis to provide the data necessary for PGE deportment.

M. A. E. HUMINICKI,P. J. SYLVESTER, L.J. Cabri, C.M. Lesher, M. Tubrett (2005) QUANTITATIVE MASS BALANCE OF PLATINUM GROUP ELEMENTS IN
THE KELLY LAKE Ni-Cu-PGE DEPOSIT, COPPER CLIFF OFFSET, SUDBURY. Economic Geology 100:1631-1646

A mineralogical mass balance has been calculated for the fraction of platinum group elements (PGE) incorporated as solid solution in sulfides and sulfarsenides and the fraction that occurs as major constituents in platinum group minerals (PGM) in the Kelly Lake Ni-Cu-PGE sulfide deposit in the Copper Cliff offset, Sudbury. Low levels of PGE in sulfides were determined quantitatively for the first time in Sudbury ores by laser ablation microprobe-inductively coupled plasma-mass spectrometry (LAM-ICP-MS), providing significantly more accurate data on the inventory and mineralogical distribution of the PGE than in previous studies. The majority of the Pt (98%), Rh (97%), and Ir (86-91%), and lesser but still large fractions of Pd (77–87%) and Ru (67–71%), occur as discrete PGM with the remainder occurring (in decreasing abundance) in solid solution in gersdorffite (1,700 ppm ΣPGE), pentlandite (1.35 ppm), chalcopyrite (0.5 ppm), and pyrrhotite (0.3 ppm). Al-though the PGE are present in low concentrations in sulfides, the abundances of these phases can be high enough to constitute a significant fraction of the total PGE. In particular, significant proportions of the Pd (14–23%) and Ru (~30%) in the Kelly Lake samples are hosted by sulfides and sulfarsenides. This has important implications for the genesis of the PGE, for the redistribution of the PGE during cooling and hydrothermal alteration, and for metal recovery during ore beneficiation.

Ilya N. Bindeman Fragmentation phenomena in populations of magmatic crystals. American Mineralogist Nov 2005, 90 (11-12) 1801-1815; DOI: 10.2138/am.2005.1645

Fragmentation of crystals is an important mechanism, and a component of particle dynamics in igneous and metamorphic rocks that has received surprisingly little attention. Recent advances in textural analysis, extraction techniques, digital imaging, and computer-assisted measurements enable rapid accumulation of 3D data on particle shapes and size distributions. This paper reviews fragment size distributions (FSD) that result from fragmentation: lognormal, fractal, loggamma, and Weibull; discusses their genesis mechanisms; and presents relevant examples of fragmentation from experi- mental physics. Next, the paper considers FSDs of feldspars on digitized images of thin sections and on published images, and quartz extracted from vesicular pumice by acid from eight well-known large-volume eruptive units. The acid solution of pumice enables examination of volume abundance, 3D shapes, proportions of fragmented crystals, and measurements of their CSDs and FSDs. FSDs were also measured in samples of welded tuff and a granite disaggregated by electric pulse. Products of syneruptive shock wave fragmentation, and fragmentation by an electric pulse are found to be fractal with large breakage probabilities, branching ratios, and fractal dimensions of 2 to 3. In contrast, most quartz fragments in pumice obey a lognormal distribution and fragmentation is driven by a melt inclu- sion decrepitation mechanism, which results in low breakage probability and small number (2−3) of fragments per breakage cycle. These results are consistent with one atmosphere heating experiments of quartz phenocrysts that led to melt inclusion decrepitation and caused quartz to break up into several smaller pieces collectively having lognormal FSD. Measured melt inclusion size distributions suggest decrepitation of outermost melt inclusions, and low survival rate for large inclusions, and inclusions with large radius/crystal size ratio. The modeling of periodic fragmentation of crystals with melt inclu- sions due to overheating and/or decompression, which may occur many times during the lifetime of a long-lived magma body, may explain concave-down, lognormal CSDs abundant in igneous rocks. The genesis of lognormality can be explained by the fragmentation algorithm of Kolmogorov (1941). Other algorithms may generate lognormal-like loggamma distributions. Fragmentation serves as an important size limiting factor, a nucleation aid, and it facilitates isotopic and trace elemental exchange.

Cabri LJ, Rudashevsky NS, Rudashevsky VN, Lastra R (2006) Hydroseparation: a new development in process mineralogy of platinum-bearing ores. CIM Bull 99(1092):1–7

Mineral processors not only need to know how the platinum-group elements (PGE) are distributed, that is, their mineralogical distribution, but the grain sizes of the platinum-group minerals (PGM), and especially the associated minerals. Common approaches, after obtaining a representative ground sample, include studying a large number of polished or polished thin sections, concentration of PGM and sulphides by different gravity methods (e.g., heavy liquids, elutriation, micro-panning), and studying the produced concentrates. Unfortunately, these methods often do not produce concentrations that are sufficiently representative of a particular ore/mineralization in all useful grain sizes. The newly developed patented technology of hydroseparation is especially effective at making concentrations of PGM over a wide range of concentrations (down to <300 ppb Pt+Pd+Au) and size fractions, including <45 μm, a size range not possible by other techniques. This water-based environmentally friendly laboratory technique provides a large amount of data from a very small amount of samples, which can range from 10 g to 2000 g or more, if required, giving con-fidence to extrapolation of results to bench-scale and larger test work, especially when combined with quantitative image analysis to determine modal percent of major minerals and mineral liberation data, needed to predict the minimum (K80) and optimum (K40) grinds.

A. Kapsiotis, T. A. Grammatikopoulos, F. Zaccarini, B. Tsikouras, G. Garuti & K. Hatzipanagiotou. Platinum-group mineral characterization in concentrates from low-grade PGE chromitites from the Vourinos ophiolite complex, northern Greece. Applied Earth Science Vol. 115 , Iss. 2,2006. DOI: 10.1179/174327506X113055

The Vourinos ophiolite complex, located in northern Greece, hosts various chromite deposits characterised by very low platinum-group element (PGE) grades. Total PGE (excluding Os) concentrations in the fourteen chromitite samples collected for use in this study varied from 200 to 300 ppb. Previous reports on the platinum-group minerals (PGM) from the Vourinos chromitites, obtained data by in-situ investigation on polished sections. Consequently, we used the technique of hydroseparation to study the PGM from the concentrates in the Vourinos chromitites. More specifically, we investigated two separate composite samples from Voidolakkos and Xerolivado chromitites. The Voidolakkos concentrate sample contains 74 PGM that include: laurite (Ru,Os)S2; irarsite (Ir,Ru,Rh,Pt)AsS; erlichmanite (Os,Ru)S2; ruthenium pentlandite; iridium (Ir(Os)); osmium (Os(Ir,Ru,Pt)); secondary phases composed of Ru, Os and Cu; alloys of Ir–Fe; Rh– and Ru–Ni–Fe alloys; and Os–Ir–Fe alloys. The investigation of Xerolivado concentrate sample yield 45 grains of PGM, including laurite, irarsite, erlichmanite, minor other PGE sulphides, Os–Ir–Ru alloys, iridium and secondary phases of Ru–Os alloys. PGM occur as both single and polyphase particles in both samples. The bulk of mineralisation in Voidolakkos is dominated by a finer variety (,10 mm) of PGM than the Xerolivado sample (mainly ,20 mm). The former occurrence hosts considerably more altered PGM grains, less laurite and a larger variety of PGM than the latter, whereas Os–Ir alloys are present in almost equal amounts in both samples. The hydroseparation process has recovered significantly more, as well as novel, PGM grains than were known from previous in-situ mineralogical examination of single chromitite samples. Although, most of the PGM occur as free particles and in-situ textural information is lost, single grain textural evidence is observed. The mineralogical and grain size differences between the two samples may reflect styles of mineralization and indicate significant remobilization of PGE. The latter possibility is suggested by the presence of secondary PGM, which may be related to the different alteration processes that affect the Voidolakkos and Xerolivado chromitites. In summary, this study provides significant new information on the particles, grain size and associations of PGM, which are critical with respect to the petrogenesis and mineral processing of these minerals.

Astakhov, A.S., Tiedemann, R., Murdmaa, I.O. et al. Manganese carbonates in the upper quaternary sediments of the Deryugin basin (Sea of Okhotsk). Oceanology (2006) 46: 716. https://doi.org/10.1134/S0001437006050122

The mineral and chemical compositions of authigenic carbonates are studied by several methods in a sediment core obtained from the axial zone of the Deryugin riftogenic basin. Manganese carbonates (kutnahorite, rhodochrosite) associated with manganiferous calcite, manganiferous pyrite, and nontronite are first identified in the Sea of Okhotsk. Manganese carbonates in the Holocene diatomaceous ooze were presumably formed due to diagenetic transformation of sedimentary manganese hydroxides, organic matter, and biogenic silica, while those found in the underlying turbidites precipitated owing to the intermittent influx of endogenic fluids migrating along sand interbeds.

Andersen,J. C. O. et al. Platinum-Group Element and Re-Os Isotope Variations of the High-Grade Kilvenjarvi Platinum-Group Element Deposit, Portimo Layered Igneous Complex, Finland. Economic Geology(2006),101(1):159

The Kilvenjärvi deposit is a high-grade platinum-group element (PGE) deposit located in the basement below the Portimo Layered Igneous Complex, Finnish Lapland. It consists of a stockwork of massive Cu-Fe-Ni sulfide veins, up to a meter wide, which cut metamorphic banded gneiss, amphibolite, and granite. The veins are surrounded by intense sulfide disseminations that are accompanied by an alteration of the basement mineral assemblage to chlorite, calcite, orthoamphibole, monazite, and an unidentified hydrous ferroaluminous silicate. The veins locally carry in excess of 110 ppm PGE, and neighboring rocks in the basement that contain disseminated sulfides locally carry 25 ppm PGE. The PGE are hosted primarily by michenerite (PdBiTe) and sobolevskite (Pd[Bi,Te]), with only very few grains of merenskyite, sperrylite, vysotskite-braggite, paolovite, cooperite, and isomertieite. The massive sulfide veins host two distinct mineral assemblages that reflect an event of sulfur addition. The primary assemblage of chalcopyrite, pentlandite, and pyrrhotite is similar to that of common orthomagmatic sulfides and appears to represent the crystallization product from a sulfide melt. However, the primary minerals have been replaced extensively by a low-temperature secondary assemblage of chalcopyrite, pyrite, marcasite, Ni-bearing pyrite, violarite, and millerite. The disseminated sulfides in the basement lithologic units comprise only the secondary assemblage and are notably richer in chalcopyrite than the massive sulfide veins. The sulfides are associated with chlorite and calcite, indicating that they were likely introduced by carbon-rich (CO2 or CH4) hydrothermal fluids. The Kilvenjärvi deposit is extremely fractionated in PGE compared to unmineralized rocks and PGE occurrences within the Portimo Complex. Os and Ir concentrations are very low, and Pd/Ir ratios reach 2.5 × 105. The massive and disseminated sulfides can be distinguished by their slightly different PGE patterns. Most notably, the massive sulfides are richest in Pd, and the disseminated sulfides are richest in Pt and Au. This fractionation appears to be consistent with an initial concentration in a magmatic sulfide melt followed by hydrothermal redistribution. The Re-Os isotopes have been significantly affected by Re mobility and cannot be used for dating. However, platinum-group mineral separates from the Kilvenjärvi deposit have nearly uniform isotopic compositions (187Os/188Os = 0.18–0.20) that are invariably higher than rocks from the Portimo Complex. Thus, it is evident that the Kilvenjärvi deposit had a significantly higher crustal contribution (possibly accounting for up to 18% of the Os) than parental magmas for the Layered series of the Portimo Complex. Contamination and fractional sulfide crystallization within the Portimo Marginal series may have been responsible for this isotopic signature. The deposit has some similarities to the various offsets associated with the Sudbury structure, Canada. A primary magmatic origin of the sulfides and PGE is evident from the mineralogy, geochemistry, and isotope geochemistry. However, the deposit has been subjected to extensive hydrothermal alteration involving carbon-rich fluids and resulting in a partial redistribution of the sulfides, PGE, and Re, extensive recrystallization, and a partial resetting of the Re-Os isotope system.

Gnos Edwin, Kurz Daniel, Eggenberger Urs (2006) Elelectrodynamic disaggregation of geologic material. 4th Swiss Geoscience Meeting, Bern

Several experiments of electrpdynamic disaggregation with different geologic material were produced. Authors emphasized that the major advantage of EPD in comparison with commercial methods (mechanical breaking) lies in the reduction of fines, the production of isometrically shaped products, and in most cases reduction of energy consumption.

Рудашевский Н.С., Рудашевский В.Н. Гидравлический классификатор. Патент на изобретение №2281808. РФ. М. 2006.

T.A. Grammatikopoulos, A. Kapsiotis, F. Zaccarini, B. Tsikouras, K. Hatzipanagiotou, G. Garuti, Investigation of platinum-group minerals (PGM) from Pindos chromitites (Greece) using hydroseparation concentrates, In Minerals Engineering, Volume 20, Issue 12, 2007, Pages 1170-1178, ISSN 0892-6875, https://doi.org/10.1016/j.mineng.2007.04.010.

The Pindos ophiolite complex, located in northern Greece, hosts small podiform chromitites characterized by very low platinum group element (PGE) grades. PGE (excluding Os) analyses from four chromitite samples, collected for this study, are below 400 ppb. Consequently, we used the technique of hydroseparation to concentrate PGM from Pindos chromitites. More specifically, we investigated two separate composite samples from Pefki and Milia chromitites. The Pefki concentrate contains 67 PGM that include secondary Ru-bearing minerals, ruarsite (RuAsS), laurite (Ru,Os)S2, irarsite (Ir,Ru,Rh,Pt)AsS, alloys of Os–Ir–Ru, hollingworthite (Rh,Pt,Pd)AsS, paolovite (Pd2Sn), braggite (Pd,Pt,Ni)S, sperrylite (PtAs2) and four unnamed PGM, electrum (Au,Ag) and native silver. The investigation of the Milia concentrate yields fifty one grains of PGM including primary laurite, Os–Ir alloys, erlichmanite, secondary Ru-bearing minerals, irarsite, Ru-alloys, ruarsite and Ru-based metals sulphides. PGM occur as both single and polyphase particles in both concentrates. The bulk of mineralization for grains between 5 and 15 lm is finer-grained in Milia (64.7%) than in Pefki (41.8%). The latter concentrate hosts considerably more altered PGM grains than the former. The hydroseparation process has recovered significantly more, as well as novel, PGM grains than the in situ mineralogical examination of single chromitite samples from the neighboring Korydallos occurrence. Although, most of the PGM occur as free particles and in situ textural information is lost, single grain textural evidence is observed. The mineralogical and grain size differences between the two samples may reflect styles of mineralization and indicate significant remobilization of PGE in Pefki. The latter possibility is suggested by the presence of secondary PGM, which may be related to the different alteration processes that affect the Pefki and Milia chromitites. In summary, this study provides significant information on the particles, grain size and associations of PGM, which are critical with respect to the petrogenesis and mineral processing of these minerals. 2007 Elsevier Ltd. All rights reserved.

Deschênes, G., Xia, C., Fulton, M., Cabri, L.J., and Price, J., 2007, “Leaching of a refractory gold ore sample from the Central Zone, Clarence Stream Property, New Brunswich, Canada,” Proceedings of the World Gold 2007, Cairns, Australia, J. Avraamides, G. Deschênes and D. Tucker, eds., AusIMM, pp. 195-203.

A cyanidation study was conducted on a mild refractory gold ore sample from the Central zone of Clarence Stream Property, owned by Freewest Resources Canada, to develop a leaching strategy to extract gold. Gold, at a grade of 8.00 g/t, is present as native gold, electrum and aurostibite. The ore also contains 2.8 per cent pyrrhotite, together with several antimony minerals (0.8 per cent berthierite and gudmundite, 0.18 per cent native antimony and stibnite). It also exhibits weak preg-robbing properties with 0.16 per cent organic carbon. Aurostibite, a gold antimony compound, is particularly known to be insoluble in cyanide solution. The antimony dissolves in cyanide solution to form antimonates, which retards gold dissolution. Industrial practice of extracting gold from aurostibite generally consists of producing a flotation concentrate, which is leached in a pipe reactor at low alkalinity and high oxygen pressure with about 20 g/L cyanide. The proposed new approach is efficient and allows the extraction of gold directly from an ore at atmospheric pressure and a low cyanide concentration at pH 10.5. The effects of grinding, pretreatment, lead nitrate, kerosene and cyanide concentrations have been investigated. The maximum gold extraction obtained on the ore was 87.9 per cent using 800 ppm NaCN, 500 g/t lead nitrate, 30 g/t kerosene, DO 10 ppm and pH 10.5 in 168 hours. The associated cyanide consumption was 1.3 kg/t. The additions of lead nitrate and kerosene increased gold extraction. In comparison to a P80 of 74 μm, a P80 of 30 μm significantly increased gold extraction. Gold in solid solution in gudmundite and arsenopyrite was believed to be responsible for the unleached fraction until mineralogical analysis of hydroseparation concentrates of leach residues showed that most of the unleached gold occurs as aurostibite, either as locked grains in sulfides/sulfarsenides or as grains with passivation rims of an Au-Sb-O phase. Coarse gold was also found. Gold extraction was not sensitive to cyanide concentration from 250 ppm to 1200 ppm NaCN and high pH was detrimental. Decreasing the cyanide concentration reduced the cyanide consumption to 0.85 kg/t. The removal of coarse gold using a Knelson concentrator and a Mosley table prior to leaching increased the gold extraction to 90.4 per cent (leach residue at 0.77 g/t).

Cabri, L.J., and Hoy, D., 2007, “Mineralogical evaluation of Au-Sb-As mineralization from the AD-MW Zones, Clarence Stream property,” Proceedings of the 39thAnnual Meeting of Can. Min. Processors, Jan. 2007, Ottawa, pp. 517-534.

Samples with contrasting gold mineralization were studied quantitatively prior to metallurgical tests. The AD samples are coarser-grained and characterized by abundant Sb minerals (jamesonite, berthierite, stibnite). The finer-grained MW sample has abundant pyrite and pyrrhotite, with arsenopyrite and galena next in abundance. A large number of gold mineral particles were determined by SEM investigation of hydroseparation concentrates, ranging from 150 to 597 per sample. The grain-size distribution of the gold minerals shows evidence of bimodal grain-size distributions (volume %), with the coarse fraction being most significant in sample MW-1 (maximum ECD=308μm). The coarsest gold minerals in the AD samples range from 139μm to 281μm ECD. The deportment of gold minerals is as electrum, aurostibite, native gold, and a possible new mineral (AuNiSb4). Gold also occurs in nisbite. The gold minerals are dominated by electrum in three samples and aurostibite is next in abundance. The major gold minerals are probably representative of three stages of gold mineralization. The first stage is represented by electrum, which is partly to completely replaced by Sb-rich mineralization forming aurostibite, and the last stage is native gold, often occurring as rims on one or the other earlier gold mineral. The gold minerals are strongly associated with sulphides in the AD samples (55 to 60 vol.%). At the grind used for the hydroseparation the liberated gold mineral quantity (volume %) is also significant, ranging from 65% for sample MW-1 to 30 to 37% for the AD samples.

Osipenko, A.B., Sidorov, E.G., Shevchenko, S.S. et al. Geochemistry and U-Pb geochronology of zircon in garnet amphibolites from Kamchatkskii Cape Peninsula, eastern Kamchatka Geochem. Int. (2007) 45: 226. https://doi.org/10.1134/S0016702907030020

The paper presents the first data on the geochemistry and U–Pb SHRIMP geochronology of zircon from garnet amphibolites whose fragments are hosted by the sole of the ophiolite complex of Kamchatskii Cape, eastern Kamchatka. The zircons compose a homogeneous sampling, have relatively small sizes, are unhedral, have no oscillatory zoning, and possess practically no inclusions. The chemistry and photoluminescent characteristics of the zircons testify to their metamorphic genesis. The U–Pb SHRIMP dates of the zircons (81.4 ± 9.6 Ma) indicate that the metamorphism of the amphibolite complex took place in Campanian time in the Late Cretaceous. These dates seem to correspond to the peak of the high-pressure metamorphism, which is thought to be related to the origin of an ophiolite complex of the suprasubduction type and its uplift within the Kronotskii Island arc.

J. GIESE, D. SEWARD, E. GNOS, D. KURZ Comparative apatite fission track study of conventionally versus selFrag Lab fragmented samples. Goldschmidt Conference Abstracts 2007. vol. A. p.322.

A small article about influence of EPD comminution on various samples for geochronological dating methods. The main conclusion - EPD does not cause annealing under the applied machine settings and to provide alternative method for rock disaggregation for apatite fission track analysis.

Will R. Goodall, Peter J. Scales, An overview of the advantages and disadvantages of the determination of gold mineralogy by automated mineralogy, Minerals Engineering, Volume 20, Issue 5, 2007, Pages 506-517, ISSN 0892-6875, https://doi.org/10.1016/j.mineng.2007.01.010.

The gold mining industry is experiencing boom times with the gold price pushing towards record levels and interest in new projects picking up. It is, however, becoming increasingly important to fully understand the intricacies of each project as more complex ores are encountered and lower grade ores are processed. This overview aims to highlight the advantages and disadvantages of using automated mineralogical and associated techniques in gaining a greater understanding of gold ore behaviour. Recent developments in techniques, such as QEMSCAN and MLA, have made them more applicable to the analysis of traditionally difficult gold-bearing ores and more accessible to the industry. These techniques are continuously challenged by the need of the industry to gain representative results, but a good understanding of their limitations can allow complementary techniques to be employed, validating the results and providing a comprehensive picture of how the mineralogy of an ore can affect its metallurgy. The nature of the complementary techniques will be examined in relation to their association and use with automated mineralogical methods.

Рудашевский Н.С., Рудашевский В.Н. Гидравлический классификатор. Патент на изобретение №69418, полезная модель. РФ. М. 2007

Oberthür, T., Melcher, F., Sitnikova, M., Rudashevsky, N.S., Rudashevsky, V.N., Cabri, L.J., Lodziak, J., Klosa, D. and Gast, L., 2008. Combination of Novel Mineralogical Methods in the Study of Noble Metal Ores – Focuson Pristine (Bushveld, Great Dyke) and Placer Platinum Mineralisation. Proceedings, 9th International Congress Applied Mineralogy (ICAM),Brisbane, Queensland, Australia, 187-194.

A combination of novel and ‘classic’ methods, namely electric pulse disaggregation (EPD), hydroseparation (HS), preparation of monolayer polished sections, and mineral liberation analysis (MLA) was employed to study ores from platinum pipes (Bushveld Complex, South Africa), pristine PGE mineralisation of the Main Sulfide Zone (Great Dyke, Zimbabwe), as well as ancient and modern gold/PGM placer deposits. It is shown here that the EPD technique liberates mineral grains of interest without any visible destruction allowing the study and analysis of individual rock-forming and ore minerals, in our case especially platinum-group minerals. The HS method is an effective tool in concentrating heavy minerals by factors up to 10 000 fold. As near-total recovery of grains >10 μm is achieved, the nugget effect can be overcome also in case of limited availability of samples (drill core, museum specimens). The MLA technique is a fast tool to detect and characterize mineral phases in ores and ore processing products. Many mineralogical parameters of individual grains and mineral assemblages can be deducted and documented. The results show that the techniques employed, either on their own or in combination, provide a wide range of additional information especially on platinum ores which is beneficial to both the researcher and the metallurgist.

Cabri LJ, Rudashevsky NS, Rudashevsky VN, Oberthür T (2008) Electric-pulse disaggregation (EPD), hydroseparation (HS) and their use in combination for mineral processing and advanced characterization of ores. Canadian Mineral Processors 40th Annual Meeting, Ottawa, Proceedings Volume 211–235.

EPD (Electric Pulse disaggregation) and HS (hydroseparation) are exceptional technologies for research, concentration, evaluation, and mineral extraction of specific minerals such as precious metals (Au, Ag, PGM), kimberlites (extraction and concentration of indicator minerals), zircons and baddeleyite (recovery of objects for geochronology), and even gemstones (method of evaluation and production of the 100% gemstone concentrate of ideal crystals) etc. EPD is used for recovery of pristine undamaged crystals of diamond, emerald, ruby, sapphire etc, including large crystals. It was tested on various hard ores and was especially successful for recovery of “soft” minerals from “hard” matrix. EPD products are very convenient for HS processing, resulting in representative concentrates of all heavy minerals including the finest particles (5-10 μm). The combined EPD and HS method enables high sensitivity (20 ppb) for evaluation of precious metal ores providing objective information about original grain size, associations, and recovery using a very small amount of sample (1-3 kg). Latest developments of EPD and HS techniques at CNT Mineral Consulting Inc. include the HS-21 hydroseparator (50 kg/hr) and the Spark-21 EPD (5 t/hr), which enables use of both techniques for prospecting and mineral processing of industrial size samples of certain ores.

Huminicki, M., Sylvester, P., Lastra, R. et al. (2008) First report of platinum-group minerals from a hornblende gabbro dyke in the vicinity of the Southeast Extension Zone of the Voisey’s Bay Ni-Cu-Co deposit, Labrador. Mineralogy and Petrology 92: 129. https://doi.org/10.1007/s00710-007-0205-5

This study reports the first documented occurrence of platinum group-minerals (PGM) in the vicinity of the Voisey’s Bay magmatic sulfide ore deposit. The PGM are present in a sulfide poor, hornblende gabbro dyke in the Southeast Extension Zone of the massive sulfide Ovoid deposit. The dyke has somewhat elevated concentrations of platinum-group elements (PGE) and gold (up to 1.95 g=t Pt, 1.41 g=t Pd, and 6.59 g=t Au), as well as Cu, Pb, Ag, Sn, Te, Bi and Sb. The PGM formed by magmatic processes and were little disturbed by subsequent infiltration of an externally-supplied hydrothermal fluid. To date, no similar PGM occurrences have been discovered in the Ovoid deposit itself. Whole rock REE patterns indicate that the dyke is geochemically related to the main conduit troctolites, which carry the bulk of the massive sulfide mineralization at Voisey’s Bay. The PGE mineralization is Pt- and Pd-rich, where the Pt and Pd occur predominantly as discrete PGM with minor Pd in solid solution in galena (average1⁄4 1.8 ppm) and pentlandite (average 1⁄4 2 ppm). The discrete PGM are predominantly hosted by disseminated base-metal sulfides (bornite, chalcopyrite, and galena) (56 vol%) and are associated with other precious metal minerals (13 vol%) with only 3 vol% of the PGM hosted by silicate minerals. In whole rock samples, the PPGE (Pt, Pd, and Rh) correlate with abundances of chalcopyrite, bornite, galena, and other precious metal minerals (PMM), whereas the IPGE (Ir, Ru, and Rh) correlate with pyrrhotite and pentlandite. There are no correlations of the PGE with chlorine. Lead isotope compositions of galena associated with the PGE mineralization in the Southeast Extension Zone are broadly similar to those for galena in the Ovoid. The lead isotope compositions are much different from those in the Voisey’s Bay Syenite, which is a potential external hydrothermal fluid source. The observed Cu-rich, Pb-rich sulfide compositions and associated Pt-Pd-Au-Ag-Sn-Te-Bi-Sb assemblage in the dyke can be produced magmatically as late ISS differentiates (e.g., Prichard et al., 2004). Melting temperatures of the PGM are also consistent with a magmatic origin. Following crystallization of PGM from magmatic sulfide, an external REE-enriched hydrothermal fluid was introduced to the system, producing secondary amphibole and locally remobilizing the Pb and Sn from the sulfides hosting the PGM.

Cabri, L.J., Y. Choi, C. H. Hamilton, P. Kondos, and R. Lastra (2008) Hydroseparation concentrates and automated precious metal searches used to characterise process products from selected mines. Ninth International Congress for Applied Mineralogy ICAM 2008. The Australasian Institute of Mining and Metallurgy, Publication Series No 8/2008, 261-264.

Hydroseparation was used to concentrate sized fractions (from <38 μm to 150 μm) of various ore products ahead of carbon-in-pulp (CIP)-treatment. The resulting size-by-size concentrates were mounted as monolayer polished sections and subjected to automated unattended precious metal searches by image analysis (see Lastra, Wilson and Cabri, 1999). Systematic variations in Au-deportment permit quantification of Au reporting as discrete grains from fresh-feed through to pressure oxidation (POX)- and CIP-feed. Application of hydroseparation, image analysis and assays to characterising tailings (from <10 μm to 106 μm) from four mine sites is also described. Results are encouraging enough to predict that the combination of hydroseparation (HS) and automated image analysis could become a standard methodology for study of precious metal ores and metallurgical products.

McDonald, A.M., Cabri, L.J., Rudashevsky, N.S., Stanley, C.J., Rudashevsky, V.N., Ross, K.C., 2008. Nielsenite, PdCu3, a new platinum-group intermetallic mineral species from the Skaergaard intrusion, Greenland.Can. Miner. 46, 709–716. DOI: 10.3749/canmin.46.3.709

Nielsenite, PdCu3, a new mineral species discovered in the Skaergaard intrusion, Kangerdlugssuaq area, East Greenland, occurs in a tholeiitic gabbro associated with plagioclase, clinopyroxene, orthopyroxene, ilmenite, titanian magnetite, fayalite and accessory chlorite-group minerals, ferrosaponite, a member of the annite–phlogopite series, hornblende, actinolite, epidote-group minerals, calcite, ankerite, apatite and baddeleyite. The mineral is found in composite microglobules principally composed of bornite–chalcocite, chalcocite, along with rare digenite, chalcopyrite, cobaltpentlandite, Co-rich pentlandite, and sphalerite. Associated platinum-group minerals include skaergaardite, keithconnite, vasilite, zvyagintsevite, (Cu,Pd,Au), (Pd,Cu,Sn) and (Pt,Fe,Cu,Pd) alloys and unnamed Au3Cu and PdAuCu. Nielsenite occurs as discrete grains or in sulfide-bearing, droplet-shaped to irregular grains that are 5–50 mm (ave: 16 mm) in size. The mineral is steel-grey in color with a metallic luster, a black streak and a sectile tenacity. No discernible forms or faces were observed. Neither cleavage nor fracture was observed, and no micro-indentation measurements were made. The mineral is non-pleochroic and exhibits neither discernible internal reflections nor evidence for twinning. It appears bright creamy white under reflected light. Reflectance values (in %) in air (in oil) are: 57.6 (47.5) at 470 nm, 60.85 (50.8) at 546 nm, 62.8 (53.0) at 589 nm and 66.7 (57.5) at 650 nm. The average result of 11 analyses is (in wt.%): Pd 29.86, Pt 3.08, Au 3.70, Cu 61.96, Fe 0.59, Pb 0.17, total 99.36%. The empirical formula (normalized to 4 apfu) is: (Pd0.862Au0.058Pt0.049Fe0.028Pb0.003)(Cu2.996Fe0.004)S3 or, ideally, PdCu3. The mineral is tetragonal, space group P4mm, with a 3.7125(8), c 25.62(1) Å, V 353.2(1) Å3 for Z = 4. The strongest six lines on the X-ray powder-diffraction pattern [d in Å(I)(hkl)] are: 2.137(100)(117), 1.8596(70)(200), 1.8337(40)(0014), 1.3126(60)(220), 1.1188(55)(317), and 1.0663 (30)(2214). Nielsenite is considered to be isostructural with synthetic tetragonal PdCu3 (P4mm). The mineral is commonly associated with skaergaardite (PdCu), which is considered to form at ~600°C under conditions of fairly high f(S2) (>7 log units). Synthetic PdCu3 forms at or below 508°C and is characterized by a relatively high degree of Pd–Cu disorder, consistent with observations made for nielsenite. The name honors Troels F.D. Nielsen, geologist with the Geological Survey of Denmark and Greenland.

CABRI,L.J.,RUDASHEVSKY,N.S.,RUDASHEVSKY,V.N.&GORKOVETZ,V.Y. (2008): Study of native gold from the Luopensulo deposit (Kostomuksha area, Karelia, Russia) using a combination of electric pulse disaggregation (EPD) and hydro-separation (HS). Minerals Eng.21, 463 – 470. DOI: 10.1016/j.mineng.2008.02.006

The mineralogy of a gold–sulphide–arsenopyrite ore from the Kostomuksha iron deposit region was studied by scanning electron microscopy (SEM) in hydroseparation (HS) products from various non-magnetic fractions (40–300 lm) after EPD crushing. The computer controlled hydroseparator CNT HS-11 produced a 100 concentration of native gold grains together with other ore minerals. Selection of >150 native gold grains from HS concentrates shows a grain size distribution of 1–154 lm (average 33 lm). Measured, upgraded gold reports as liberated grains (46.0%), as intergrowths with arsenopyrite (14.2%), lo ̈llingite (19.7%), native bismuth (17.1%), and in association with pyrrhotite (0.9%) and chlorite/apatite (2.0%). High recoveries of native gold are explained in terms of the combined effects of selective grain-boundary fracture induced by EPD crushing, resulting in preservation of metallic mineral aggregates and grain boundaries, even within large native Au/Bi particles (such soft particles would otherwise show significant changes during normal comminution methods). High gold recoveries should thus be possible using traditional gravity and flotation followed by cyanidation. A combined EPD/HS protocol demonstrates the unique possibilities of this technology for laboratory-scale gravity recoverable gold (GRG) testing.

Cabri, L.J., Rudashevsky, N.S., Rudashevsky, V.N. (2008) Current approaches for the process mineralogy of platinum-group element ores and tailings. Ninth International Congress for Applied Mineralogy ICAM 2008. The Australasian Institute of Mining and Metallurgy, Publication Series No 8/2008, 9-17.

Characterisation of platinum-group element (PGE) deposits and their process products has many challenges for the process or applied mineralogist. It is now well established that the PGE distribution for such samples is variably divided between submicroscopic concentrations of PGE in sulfides, tellurides and related minerals occurring as discrete platinum-group minerals (PGM), of which there are a large number of species, many with partial replacement between the PGE and between anions. Each PGE deposit type requires a targeted approach but fundamentally, there are two general methodologies in vogue. One way is to make a large number of polished or polished thin sections for detailed scanning electron microscopy (SEM)/optical examination to determine the PGM distribution and their associations and grain sizes. The other is to make concentrates of representative crushed or processed samples, thus having fewer subsamples to examine. Our method of choice is to use hydroseparation (HS) for concentration. HS provides representative concentrates of sizes down to ~10 μm, not possible by other techniques. Various microbeam methods have been used for analysis of trace quantities of PGE (EPMA, micro-PIXE, SIMS and LAM-ICPMS). We prefer LAM-ICPMS (laser ablation microprobe – inductively coupled mass spectrometry) because of the relatively large analytical volume sampled, the ability to measure all the PGE, monitor up to 20 elements, together with detection levels in the tens to a few hundreds of ppb. We provide typical results derived in studies of stratiform PGE ores and tailings, and a massive Ni-Cu sulfide ore.

T. Oberthür, F. Melcher, M. Sitnikova, N. S. Rudashevsky, V. N. Rudashevsky, L. J. Cabri, J. Lodziak, and D. Klosa A novel mineralogical approach in the study of noble metal ores: Example Platinum Pipes of the Bushveld Complex, South Africa. SEG-GSSA Conference 2008 ., At Misty Hills, Jonannesburg, South Africa, Volume: Abstract Volume, 153-157

The study of noble metal ores is generally hampered by comparatively low grades of the ores (1-10 g/t) and the “nugget effect”. For example, at an average grain size of 100 μm and at a grade of 100 ppm, about 5-10 polished sections are needed to detect one discrete grain of gold or PGM (Ney, 1977). Consequently, laborious and time-consuming studies are necessary in order to obtain statistically sound data on gold and PGM ores and, finally, to advance the genetic understanding and metallurgical treatment of ores. The genesis of the platiniferous pipes of the eastern Bushveld Complex is still enigmatic. Orthomagmatic, metasomatic replacement, and hydrothermal models were proposed (e.g. Scoon and Mitchell, 2004). Advance in the understanding of the pipes, also within the wider frame of PGE mineralization of the Bushveld Complex, has limitations as these orebodies were mined out early in the last century and material is available from museum collections only. We have applied a combination of novel and “classic” methods, namely electric pulse disaggregation (EPD), hydroseparation (HS), preparation of monolayer polished sections, and mineral liberation analysis (MLA) in the study of ores from the platinum pipes of the Bushveld. We report on the results and give a preliminary account of the PGE mineralogy of the pipes.

JOAQUÍN A. PROENZA, FEDERICA ZACCARINI, NICOLAY RUDASHEVSKY, LOUIS J. CABRI, GIORGIO GARUTI, VLADIMIR N. RUDASHEVSKY, JOHN F. LEWIS, FRANCISCO LONGO, SALVADOR GALÍ, MANUEL LABRADOR, ESPERANZA TAULER, GIOVANNI BLOISE (2008) Platinum Group Minerals (PGM) in Ni-Laterites from Falcondo, Central Dominican Republic. Reunión de la Sociedad Española de Mineralogía, Volume: Macla

Previous studies have suggested that lateritic weathering could play an important role in the neo-formation of platinum group mineral (PGM), and that laterites have a potential for PGE research (Bowles, 1986; Grey et al., 1996). The behaviour of PGE in this environment is not yet completely understood, although some examples of well documented remobilization and precipitation/enrichment of PGE in lateritic environments already exist (Salpeteur et al., 1995; Traoré et al., 2008). In this study, one saprolite sample from a Ni-lateritic profile (Central Dominican Republic) have been investigated using innovative Electric Pulse Disaggregation (EPD) and hydroseparation (HS) techniques (Rudashevsky et al., 2002) with the aim of determining the occurrence of the platinum group minerals (PGM).

Will R. Goodall, Characterisation of mineralogy and gold deportment for complex tailings deposits using QEMSCAN®, Minerals Engineering, Volume 21, Issue 6, 2008, Pages 518-523, ISSN 0892-6875, https://doi.org/10.1016/j.mineng.2008.02.022.

A comprehensive understanding of mineralogical associations and gold deportment is important for identification of the causes of gold losses to tailings and in development of re-treatment procedures to recover this value. Recent advances in the QEMSCAN system to enhance false positive identification have increased the speed and accuracy of gold particle determination. This increased capability has been combined with a suite of complementary diagnostic chemical techniques to provide a complete methodology for accurate and economic analysis of tailings material. Through this methodology the advantages of combining automated mineralogical techniques with more traditional diagnostic chemical assay have been demonstrated through a case study examining the flotation tailings stream of a Cu–Au operation in North Queensland, Australia. Outcomes of the case studyindicated that a significant portion of gold losses were attributable to coarse free gold present in the flotation tailings.

CABRI, L.J., MARTIN, C.J. & NElSON, M. (2009): Deportment methodology for low-grade Ni–Cu–PGE ores. Proc. 48th Conf. Metallurgists (C. Hamilton, B. Hart & P.J. Whit-taker, eds.), 3-15.

The metallurgical response of platinum-group element (PGE) ores to conventional grinding and bulk flotation is driven by (a) the distribution of PGE as discrete platinum-group minerals (PGM), (b) the speciation of PGM, and their size range, (c) the deportment of PGE in host sulphides and (d) the degree of alteration of the host rock. Accordingly, characterising such materials is a complex exercise, and a challenge to the applied mineralogist. In a recent case study, we will describe how PGM balancing using gravity pre-concentration and SEM techniques, automated mineralogical analysis of host sulphide and non-sulphide minerals, and analysis of host sulphides using LAM-ICPMS (laser ablation microprobe - inductively coupled mass spectrometry) were integrated to characterise such PGE-bearing materials. We also describe how these data can be used to predict likely metallurgical response.

Gonzáles-Jiménez JM, Gervilla F, Proenza JA, Augé T, Kerestedjian T (2009) Distribution of platinum-group minerals in ophiolitic chromitites. Appl Earth Sci (Trans Inst Min Metall B) 118:101–110. DOI: 10.1179/174327509X12550990457924

This paper reviews the distribution of platinum-group minerals in ophiolitic chromitites. Our data and literature data, obtained by in-situ investigation of polished sections and techniques of mechanical separation [hydroseparation (HS), or combining electric pulse disaggregation (EPD) plus HS], are contrasted. Finally, in-situ textural data are used as platform criteria to compare the different proposed models that attempt to explain the origin of the platinum-group mineral assemblages found in ophiolitic chromitites.

Deschenes, G., Xia, C., Fulton, M., Cabri-Louis, J. & Price, J. (2009). Evaluation of leaching parameters for a refractory gold ore containing aurostibite and antimony minerals: part I – central zone. Minerals Engineering, 22, 799–808. DOI: 10.1016/j.mineng.2009.02.003

A cyanidation study was conducted on a mild refractory gold ore sample from the Central zone of Clarence Stream Property, owned by Freewest Resources Canada, to develop a leaching strategy to extract gold. Gold, at a grade of 8.00 g/t, is present as native gold, electrum and aurostibite. The ore also contains 2.8% pyrrhotite, together with several antimony minerals (0.8% berthierite and gudmundite, 0.18% native antimony and stibnite). It also exhibits weak preg-robbing properties with 0.16% organic carbon. Aurostibite, a gold antimony compound, is particularly known to be insoluble in cyanide solution. The antimony dissolves in cyanide solution to form antimonates, which retards gold dissolution. Industrial practice of extracting gold from aurostibite generally consists of producing a flotation concentrate, which is leached in a pipe reactor at low alkalinity and high oxygen pressure with about 20 g/L cyanide. The proposed new approach is efficient and allows the extraction of gold directly from an ore at atmospheric pressure and a low cyanide concentration at pH 10.5. The effects of grinding, pre-treatment, lead nitrate, kerosene and cyanide concentrations have been investigated. The maximum gold extraction obtained on the ore was 87.9% using 800 ppm NaCN, 500 g/t lead nitrate, 30 g/t kerosene, DO (dissolved oxygen) 10 ppm and pH 10.5 in 168 h. The associated cyanide consumption was 1.3 kg/t. The additions of lead nitrate and kerosene increased gold extraction. In comparison to a P80 of 74 lm, a P80 of 30 lm significantly increased gold extraction. Gold in solid solution in gudmundite and arsenopyrite was believed to be responsible for the un-leached fraction until mineralogical analysis of hydroseparation concentrates of leach residues showed that most of the un-leached gold occurs as aurostibite, either as locked grains in sulphides/sulpharsenides or as grains with passivation rims of an Au–Sb–O phase. Coarse gold was also found. Gold extraction was not sensitive to cyanide concentration from 250 to 1200 ppm NaCN and high pH was detrimental. Decreasing the cyanide concentration reduced the cyanide consumption from 1.39 to 0.85 kg/t. The removal of coarse gold using a Knelson concentrator and a Mosley table prior to leaching increased the gold extraction to 90.4% (leach residue at 0.77 g/t).

Uysal, I.; Zaccarini, F.; Sadiklar, M.B.; Bernhardt, H.J.; Bigi, S.; Garuti, G. Occurrence of rare Ru-Fe-Os-Ir-oxideand associated Platinum-group minerals (PGM) in the chromitite of Mugla ophiolite, SW-Turkey.Neues Jahrb.Mineral. Abhand.2009,185, 323–333. DOI: 10.1127/0077-7757/2009/0131

A number of podiform chromitites, associated with different ophiolites, proved to contain minute grains, generally less than 15 microns in size, of unusual Platinum-group mineral (PGM) composed of Ru-Fe-Os-Ir and O (Garuti & Zaccarini 1997, Garuti et al. 1999a, b, Zaccarini et al. 2005, Proenza et al. 2007, 2008, Tsoupas & Economou-Eliopoulos 2008). In this contribution, we describe a further occurrence of oxidized PGE compounds from chromitites of the Muğla ophiolite complex, located in SW Turkey. A number of grains, with a size comprised between 20-60 μm, were found in heavy concentrates obtained using the hydroseparation technique. The electron microprobe analysis of these grains, liberated from their including matrix, are not affected by spurious fl uorescence caused by the direct or secondary excitation of the adjacent phases and confi rms the presence of oxygen as major constituent of the PGM. Some grains contain Si and Mg up to 9.1 and 10.4 at%, respectively. The Si and Mg are positively correlated (r = +0.92) but do not correlate with any other elements including oxygen. This evidence strongly supports the observation that the oxidized PGM contain sub-microscopic particles of chlorite or serpentine. In all the analyzed grains the content of PGE is higher than that of Fe, and their compositions in terms of Ru-Os-Ir overlap the fi eld of coexisting laurite. This observation confi rms the conclusion that the oxidized PGE compounds derived from desulfurization of laurite at low temperature, with substitution of the removed S by Fe and O. In contrast with the chromitites from Vourinos where these oxides formed under weathering conditions (Garuti & Zaccarini 1997), the paragenetic assemblage (ferrian chromite, serpentine, chlorite) of the Ru-Fe-Os-Ir oxides of Muğla indicates that the origin of these PGM is compatible with rodingitization and serpentinization under hydrothermal conditions as it was proposed for the chromitites of the Urals (Garuti et al. 1997, Zaccarini et al. 2004) or under metasomatic fl uids released along shear zone, as suggested for the Veria chromitites (Tsoupas & Economou-Eliopoulos 2008).

ZACCARINI,F.,PROENZA, J.A., RUDASHEVSKY, N.S., CABRI, L.J., GARUTI, G.,RUDASHEVSKY, V.N.,MELGAREJO, J.C., LEWIS, J.F., LONGO, F.,BAKKER, R.&STANLEY,C.J. (2009).The Loma Peguera ophiolitic chromitite (Central Dominican republic): A source of new platinum group minerals (PGM) species. Neues Jahr Mineral Abh 185, 335–349. DOI: 10.1127/0077-7757/2009/0127

Platinum group element (PGE) rich ophiolitic chromitites associated with the Loma Peguera harzburgitic mantle have been investigated for Platinum group minerals (PGM) using electric pulse disaggregation (EPD) and hydroseparation (HS) techniques. Combination of these two techniques allows for effi cient concentration of the heavy minerals, including PGM. The PGM have been analyzed by electron microprobe, by Raman spectroscopy and investigated for their refl ectivity. The majority of the discovered PGM, on the basis of their chemical composition and optical properties, potentially represent new mineral species, including Ru,Os,Ir,Fe compounds, Ir(Fe,Ni)3, Ir(Ni,Fe)3, (Ir,Pt)(Fe,Ni), Pt(Ni,Fe)3,(Ru,Pt)(Fe,Ni), (Fe,Ru,Ni,Os,Ir,Co)2S and Rh,Ni,As. One disadvantage of an investigation of concentrates is that some in situ textural information is lost. However, on the basis of their morphology and some attached associated minerals, the presence of oxygen, altered chromite, and serpentine, we can argue that most of the discovered PGM are secondary in origin, i.e. formed at low temperature during post magmatic processes.

Giese, J., Seward, D., Stuart, F. M., Wüthrich, E., Gnos, E., Kurz, D., Eggenberger, U. and Schreurs, G. (2009), Electrodynamic Disaggregation: Does it Affect Apatite Fission-Track and (U-Th)/He Analyses?. Geostandards and Geoanalytical Research, 34: 39–48. doi:10.1111/j.1751-908X.2009.00013.x

This article describes the principle of electric pulse disaggregation. On the example of some apatite rocks, the difference of U-Th/He ages were studied. It was observed, that ages of ED seaparated apatites were indistinguishable from those measured on apatites extracted using conventional mechanical techniques.

Rudashevsky V.N., Kretser Yu.L., Rudashevsky N.S., Nielsen T.F.D. Gold, PGE and sulphide phases of the precious metal mineralisation of the Skaergaard intrusion. Part 6: sample 90-23A, 798. Geological Survey of Denmark and Greenland, Ministry of the environment (GEUS) Report 2009. 48, 2003. 46 p.

This is one of several mineralogical reports on the noble mineralization of the Skaergaard. From HS-concentrates polished mounts were prepared. 72 precious metal grains were found in the monolayer mounts from 1 sample. Average grain size is 17 μm.

Rudashevsky N.S., Kretser Yu.L., Rudashevsky V.N., Nielsen T.F.D. Gold, PGE and sulphide phases of the precious metal mineralisation of the Skaergaard intrusion. Part 7: sample 90-18, 958 // Geological Survey of Denmark and Greenland, Ministry of the environment (GEUS) Report 2009/ 68, 2009. 47 p.

This is one of several mineralogical reports on the noble mineralization of the Skaergaard. From HS-concentrates polished mounts were prepared. 33 particles and 37 grains were found in the monolayer mounts from 1 sample (0,9 kg). Average grain size is 22,5 μm.

Malarkey J, Pearson DG, Kjarsgaard BA et al (2010) From source to crust: tracing magmatic evolution in a kimberlite and a melilitite using microsample geochemistry. Earth Planet Sci Lett 299:80–90. DOI: 10.1016/j.epsl.2010.08.020

We present an integrated microsampling trace element and isotopic study of primary minerals within the Jos kimberlite, Canada, in order to observe how different phases record progressive crustal interaction in the evolving kimberlite. Identification of the least contaminated phases provides the best information on kimberlite source geochemistry. We also carried out an analogue study on an olivine melilitite from Saltpetre Kop, South Africa, examining a similar mineral suite, with the addition of melilite. The two studies show that all phases except phenocryst olivine show some evidence of crustal modification. Perovskite has recently been used as a proxy for source isotope composition. Although perovskite may provide a better constraint on the isotopic composition of the kimberlite than the whole rock, it does not necessarily provide the best constraint on the source region. The lower initial 87Sr/86Sr ratio recorded by early crystallising phases in the kimberlite is similar to those of the low-Cr megacryst suite, strengthening the genetic relationship between kimberlite activity and megacryst formation.

Oberthür, T., Melcher, F., Sitnikova, M., (2010) Advances in the study of platinum mineralization by combining novel and classic mineralogical and geochemical methods. 11th International Platinum Symposium, At Sudbury, Canada. Abstract Volume

Combinations of methods like electric pulse disaggregation (EPD), hydroseparation (HS), preparation of monolayer polished sections, and mineral liberation analysis (MLA), were employed to study ores from pristine PGE mineralization and PGM placer deposits. It is shown here that the EPD technique readily liberates mineral grains of interest without any visible destruction. The HS method effectively concentrates heavy minerals by factors up to 10,000 fold; near-total recovery of grains >10 um leads to overcoming the nugget effect especially in case of limited availibility of samples (drill core, museum specimens). The MLA technique is a fast tool to detect and characterize minerals in ores and processing products. Many mineralogical parameters of individual grains and mineral assemblages can be documented. The results show that the techniques employed, either on their own or in combination, provide a wide range of additional information especially on platinum ores which is beneficial to both the researcher and the metallurgist.

Cabri LJ, Choi Y, Nelson M, Tubrett M, Sylvester PJ (2010) Advances in precious metal trace element analyses for deportment using LAM-ICPMS. In Proc. 42nd Annual meeting Can Mineral Pro-cessors 181–196.

The development and characterization of sulphide standards containing as many as seven precious metals has increased the efficiency and comprehensiveness of micro-analyses for deportment studies using laser ablation microprobe inductively coupled plasma mass spectrometry (LAM-ICPMS). Because trace precious metals occurring in solid solution or as sub-micron inclusions in sulphides, arsenides, and sulpharsenides are often heterogeneously distributed, a significantly large number of analyses are required. Using well-prepared samples it is possible for up to 120 analyses per day, far more than by other comparable methods. Examples will be discussed from projects focused on the deportment of Au and the platinum-group elements (PGE).

LOCMELIS, M., MELCHER, F., and OBERTHÜR, T. 2010. Platinum-group element distribution in the oxidized main sulfide zone, Great Dyke, Zimbabwe. Mineralium Deposita, vol. 45. pp. 93–109.

In the Great Dyke mafic/ultramafic layered intrusion of Zimbabwe, economic concentrations of platinum-group elements (PGE) are restricted to sulfide disseminations in pyroxenites of the Main Sulfide Zone (MSZ). Oxidized ores near the surface constitute a resource of ca. 400 Mt. Mining of this ore type has so far been hampered due to insufficient recovery rates. During the oxidation/weathering of the pristine ores, most notably, Sand Pd are depleted, whereas Cu and Au are enriched. The concentrations of most other elements (including the other PGE) remain quite constant. In the oxidized MSZ, PGE occur in different modes: (1) as relict primary PGM (mainly sperrylite, cooperite, and braggite), (2) in solid solution in relict sulfides (dominantly Pd in pentlandite, up to 6,500 ppm Pd and 450 ppm Pt), (3) as secondary PGM neoformations (i.e., Pt–Fe alloy and zvyagintsevite), (4) as PGE oxides/hydroxides that replace primary PGM as the result of oxidation, (5) hosted in weathering products, i.e., iron oxides/hydroxides (up to 3,600 ppm Pt and 3,100 ppm Pd), manganese oxides/hydroxides (up to 1.6 wt.% Pt and 1,150 ppm Pd), and in secondary phyllosilicates (up to a few hundred ppm Pt and Pd). In the oxidized MSZ, most of the Pt and Pd are hosted by relict primary and secondary PGM; subordinate amounts are found in iron and manganese oxides/hydroxides. The amount of PGE hosted in solid solution in sulfides is negligible. Considerable local variations in the distribution of PGE in the oxidized ores complicate a mineralogical balance. Experiments to evaluate the PGE recovery from oxidized MSZ ore show that using physical concentration techniques (i.e., electric pulse disaggregation, hydroseparation, and magnetic separation), the PGE are preferentially concentrated into smaller grain size fractions by a factor of 2. Highest PGE concentrations occur in the volumetrically insignificant magnetic fraction. This indicates that a physical preconcentration of PGE is not feasible and that chemical, bulk-leaching methods need to be developed in order to successfully recover PGE from oxidized MSZ ore.

Kozlu H., Rudashevsky V.N. (2010) Geochemistry of the Platinum-Group Minerals (PGM) in the Chromitites from Elbistan-Berit Mantle Transition Zone and Kızıldağ (Hatay) Ophiolite, SE-S Turkey. 11th Int. Platinum Symp. (Sudbury). Ontario Geol. Surv., Misc. Release – Data, 269.

The Berit ophiolite is located in the Tauride thrust belt of southeast Turkey. The Berit chromitites contain Pt (10 to 1155 ppb) and Pd (3 to 2518 ppb) enrichments. The Kızıldağ ophiolite is one of the best-preserved Neothetyan oceanic lithospheric remnants in southern Turkey. Total platinum group element (PGE) content of the Kızıldağ chromitite samples ranges from 94 to 334 ppb. Twenty PGM grains have been determined, such as irarsite, native iridium, braggite, Pt-Fe alloys, Pt-Cu alloys, tulameenite, tetraferroplatinum, sperrylite, potarite, stibiopalladinite, and tischendorfite. These grains were recovered in high-Al chromitite (Al2O3 38.5 wt%) from Berit (MBD-13) by means of extensive mineral processing, including both Electric-Pulse Disaggregation (EPD) and hydroseparation (HS). Seventeen PGM grains found in the Kızıldağ chromitite (HAK-16 A, Al2O3 24.9 wt%) are laurite, erlichmanite, native iridium, native osmium, native palladium, Pt-alloys and irarsite. Because both chromitite deposits are of ophiolitic origin, although having high-Al chromitite compositions, the results indicate that they are both enriched in PGE: PPGE (Berit) or IPGE (Kızıldağ). Berit chromitites are significant with their PGM-bearing sulphide droplets. Our results for the high-Al chromitites in the Berit ophiolite suggest that they have a more fertile potential PPGE enrichments for ophiolitic podiform chromitites.

CABRI, L.J. (2010): Process mineralogy in the Pt industry and future trends. In Abstr. 11th Int. Platinum Symp. (Sudbury). Ontario Geol. Surv., Misc. Release – Data, 269.

There are no formal courses available in process or applied mineralogy in spite of international meetings, several proceedings, and related publications on the subject since the early 1980s. When this is considered in the context of the historical secrecy in the platinum mining industry, a large divide has been created with classical/geochemical methods more suitable for genetic studies. On the other hand, the world’s major producer of platinum-group elements (PGE) is a leader in applying some of the latest automated techniques to monitor their mineral processing activities. Some of these techniques, such as using automated SEM-based image analysers are also used by many other major mining companies and research organizations. However, there are also other approaches useful in characterizing ores and ore products, such as electric pulse disaggregation (EPD) and electric hydraulic (EH) processing. On the other hand, the exploration and genetic focus of some, especially in academia, risks having an important and innovative group of scientists not making full use of appropriate methodology in characterizing ores by obtaining the quantitative parameters most useful to those engaged in mineral processing and beneficiation.

McDonald, A.M., Proenza, J., Zaccarini, F., Rudashevsky, N., Cabri, L.J., Stanley, C.J., Rudashevsky, V., Melgarejo, J.C., Lewis, J., Longo, F., and Bakker, R.J. (2010) Garutiite, (Ni, Fe, Ir) a new hexagonal form of native Ni from Loma Peguera, Dominican Republic. European Journal of Mineralogy, 22, 293–304. DOI: 10.1127/0935-1221/2010/0022-2007

Garutiite (Ni,Fe,Ir) is a new hexagonal polymorph of native Ni discovered in chromitite from Loma Peguera, Dominican Republic. The mineral was identified in heavy mineral concentrates obtained through the use of electric pulse disaggregation (EPD) and hydroseparation (HS) techniques. It forms as anhedral, botryoidal grains typically 10–60 mm in size (maximum of 110 mm). Grains are single or composite, frequently porous and zoned, and occasionally display an unusual lamellar internal texture. Associated minerals include hexaferrum, ferrian chromite, chlorite-group minerals, serpentine-group minerals, awaruite, irarsite, laurite, native Ru and unidentified species including Ru–Os–Ir-Fe and Pt–Ni–Fe–Ir compounds, Pt(Ni,Fe)3, (Fe,Ru,Ni,Os,Ir,Co)2S and RhNiAs. The mineral is megascopically grey to grey-black with a metallic luster. In plane-polarized light, garutiite is white in color, exhibits a very weak anisotropy, and no pleochroism, bireflectance or internal reflections were observed. No cleavage was noted and the hardness could not be determined owing to the porous nature of the mineral. The calculated density is 11.33 (1) g/cm3. Reflectance values (%) in air are: 63.8 at 470, 65.9 at 546, 67.0 at 589 and 68.0 at 650 nm. The average result of electron microprobe analyses (n 1⁄4 42 from 27 grains) is: Ni 27.91, Fe 19.94, Ir 43.78, Pt 6.98, Co 0.55, Cu 0.43, Ru, 0.50, Rh 0.74, Os 0.67, total 101.51 wt%, corresponding to (Ni0.421Fe0.316Ir0.202Pt0.032Co0.008Cu0.006Rh0.006Ru0.004Os0.003)P1 or the simplified formula, (Ni,Fe,Ir). Garutiite is the Ni analogue of hexaferrum, osmium and ruthenium and is classified as belonging to the osmium group. As such, the mineral is considered to be hexagonal, crystallizing in space group P63/mmc with a 2.6941(4) and c 4.2731(6) A ̊ , V 1⁄4 26.86(1) A ̊ 3, Z 1⁄4 2. The strongest lines of the X-ray powder diffraction pattern [d(in A ̊ )(I)(hkl)] are: 2.330(50)(100), 2.136(30)(002), 2.046(100)(101), 1.576(30)(102), 1.3470(40)(110), 1.2155(40)(103). Based on its morphology, internal texture, and the associated minerals, garutiite is interpreted to be secondary in origin, i.e., having formed at low temperatures during post magmatic processes, such as serpentinization and/or lateritization. The name honors Prof. Giorgio Garuti, in recognition of his contributions to the understanding of the mineralogy of platinum-group elements.

K. A. Dyl, E. D. Young (2010) ELECTRIC PULSE DISAGGREGATION OF CV3 METEORITES: CHARACTERIZATION AND OXYGEN ISOTOPIC ANALYSES OF MATRIX. 73rd Annual Meteoritical Society Meeting

EPD technology finds application even in the study of cosmic material. Due to this unique method of disaggregation scientists were able to break up even a tiny pieces of meteorites into their individual nebular components. Follow-up studies revealed, that matrix of CV3 meteorites characterized by a more 16O-rich composition. The research continues.

Malitch, K.N., Belousova, E.A., Griffin, W.L. et al. Magmatic evolution of the ultramafic-mafic Kharaelakh intrusion (Siberian Craton, Russia): Insights from trace-element, U-Pb and Hf-isotope data on zircon. Contrib Mineral Petrol (2010) 159: 753. https://doi.org/10.1007/s00410-009-0452-z

The ultramafic–mafic Kharaelakh intrusion in the northwestern part of the Siberian Craton (Russia) hosts major economic platinum-group-element (PGE)–Cu–Ni sulphide deposits. In situ U–Pb, REE and Hf-isotope analyses of zircon from these rocks, combined with detailed study of crystal morphology and internal structure, identify four zircon populations. U–Pb ages of these populations cover a significant time span (from 347 ± 16 to 235.7 ± 6.1 Ma) suggesting multiple magmatic events that cluster around 350 and 250 Ma, being consistent with two recognised stages of active tectonism in the development of the Siberian Craton. The oldest zircon population, how-ever, represents previously unknown stage of magmatic activity in the Noril’sk area. Epsilon-Hf values of ?2.3 to?16.3 in the analysed zircons reflect a dominant role of mantle-derived magmas and suggest that juvenile mantle material was the main source for the ultramafic–mafic Kharaelakh intrusion. A significant range in initial 176Hf/177Hf values, found in zircons that cluster around 250 Ma, indicate mixing between mantle and crustal magma sources. Our findings imply that economic intrusions hosting PGE–Cu–Ni deposits of the Noril’sk area have a far more complex geological history than is commonly assumed.

Rudashevsky N.S., Rudashevsky V.N., Nielsen T.F.D. PGE and sulphide phases of the precious metal mineralisation of the Skaergaard intrusion, Part 8: sample 90-18, 972. Geological Survey of Denmark and Greenland, Ministri of the Environment. (GEUS). Report 2010/73. 2010a. 59 pp.

This is one of several mineralogical reports on the noble mineralization of the Skaergaard. 60 PGM-grains were enriched into heavy concentrates from the sample (0,8 kg) by means of the new hydroseparator HS-11. Results of mineralogical analysis through mass balance calculation are very close to assays of whole-rock .

Rudashevsky N.S., Rudashevsky V.N., Nielsen T.F.D. Gold, PGE and sulphide phases of the precious metal mineralisation of the Skaergaard intrusion, Part 9: sample 90-18, 978. Geological Survey of Denmark and Greenland, Ministri of the Environment. (GEUS). Report 2010/74. 2010 b. 75 pp.

This is one of several mineralogical reports on the noble mineralization of the Skaergaard. The HS-concentrates of sample yielded 157 grains of PGMs. The grain size varies from 2 to 74 μm with average grain size of 27 μm. HS-concentrates allows to show real grain size distribution within precious metal mineralisation.

Rudashevsky N.S., Rudashevsky V.N., Nielsen T.F.D. Gold, PGE and sulphide phases of the precious metal mineralisation of the Skaergaard intrusion, Part 10: sample 90-18, 988. Geological Survey of Denmark and Greenland, Ministri of the Environment. (GEUS). Report 2010/85. 2010c. 39 pp.

This is one of several mineralogical reports on the noble mineralization of the Skaergaard. From HS-concentrates polished mounts were prepared. 33 particles and 41 precious metal mineral grains were found in the monolayer mounts from 1 sample (0,8 kg). Average grain size is 12 μm. Besides usual PGM, some rare and unnamed phases were found and described.

Rudashevsky N.S., Rudashevsky V.N., Nielsen T.F.D. Gold, PGE and sulphide phases of the precious metal mineralisation of the Skaergaard intrusion, Part 11: sample 90-24, 1062. Geological Survey of Denmark and Greenland, Ministri of the Environment. (GEUS). Report 2010/138 2010d. 39 pp. HS-PGM-Au

This is one of several mineralogical reports on the noble mineralization of the Skaergaard. 33 PGM-grains were recovered from 1 sample (1,3 kg) using hydroseparator. Average grain size is 12 μm. Besides usual PGM, some rare and unnamed phases were found. All the observations and the intergrain relations suggest that all PGMs form a single paragenesis.

Aiglsperger T., Proenza J.A. , Manuel Labrador, Zaccarini F., Garuti G., (2011) Geochemistry and Mineralogy of PGE in the Falcondo Ni-laterite Deposits, Dominican Republic. Conference: 11th Biennial Meeting of the Society for Geology Applied to Mineral Deposits (SGA), At Antofagasta (Chile)

Two laterite profiles from the Falcondo Ni- laterite deposit in the Dominican Republic have been analysed to their PGE contents. General PGE enrichment is observed in both profiles close to the exposed limonitic horizon as well as within the saprolitic horizon. Chondrite normalized patterns of the saprolite and limonite show flat PGE trends similar to average mantle peridotites. PGE enrichment is mainly controlled by the presence of chromitites, however, supergene processes have influenced the re-distribution of PGE, leading to local enrichments of these elements, especially in the upper limonite. One limonite sample (total PGE content 212 ppb) and one saprolite sample (total PGE content 62 ppb) have been investigated for PGM using hydroseparation (HS) technique. In both samples PGM were found included in bigger, progressively weathered awaruite and chromite, whereas irregular shaped free grains of PGM were limited to the saprolite sample. All detected PGM grains are smaller than 20 μm in diameter and mainly consist of Ru-Os-Ir-Fe phases. The possibility of finding precious metals as mineral compounds within the highest horizons of Ni-laterites can play an important role for exploration projects in the future.

Aiglsperger T, Proenza JA, Zaccarini F, Labrador M, Navarro-Ciurana D (2011) Looking for needles in a haystack: how to find PGM in laterites by using hydroseparation techniques. Macla 15: 23–24

Taking their great potential as future ore resources into account, surprisingly few detailed studies on Platinum Group Minerals (PGM) found within supergene environments have been done. In particular, our current knowledge of PGM in laterites that overlie mafic to ultramafic bodies in tropically weathered regions is mainly based on the works of Augé (1994), Bowles (1986), McDonald (1999) and Salpeteur (1995). One possible explanation for the lack of further investigations in this field could be the fact that sample preparation is highly time consuming with very limited chances to find PGM by using traditional concentration techniques such as panning. Generally low total PGE contents of laterite samples combined with usually very small grain sizes of PGM (<40 μm) are the main challenges when trying to find PGM in laterites. In this work we present the innovative hydroseparation technique HS 11 (developed by CNT-MC Inc., St. Petersburg) which was recently installed in the HS 11 laboratory at the University of Barcelona, by demonstrating the complete separation procedure for PGE- bearing laterite samples from the Dominican Republic. Because of its unique advantages when it comes to very small grain sizes, this non-chemical concentration technique will certainly play a key role in future laterite linked PGM investigation.

KELVIN,M.A. SYLVESTER, P.J. & CABRI,L.J. (2011): Mineralogy of rare occurrences of precious-metal-enriched massive sulfide in the Voisey’s Bay Ni-Cu-Co Ovoid Deposit, Labrador, Canada. Can Mineral 49, 1505 – 1522. DOI: 10.3749/canmin.49.6.1505

The Voisey’s Bay Ovoid Ni–Cu–Co magmatic sulfide deposit, Labrador, is generally poor in precious metals (Pt, Pd, Ag, Au), but unusual occurrences with elevated levels (Pt + Pd > 0.5 ppm) are present. In this paper present a quantitative description of the precious-metal mineralogy of four such occurrences within massive sulfides. The four samples, all from near the center of the Ovoid, were examined by SEM-based Mineral Liberation Analysis for characterization of precious-metal minerals/The results indicate that the majority of precious metals are present as discrete mineral phases including sperrylite, froodite, michenerite, Au–Ag alloy, volynskite, stützite and acanthite, whereas minor to moderate amounts of Pt, Pd, Ag and Au are found in solid solution in pyrrhotite, pentlandite, chalcopyrite and galena. The precious-metal minerals are normally associated with pentlandite, galena, chalcopyrite pyrrhotite and magnetite, and rarely with breithauptite (NiSb), altaite (PbTe), other precious-metal minerals and native bismuth.

McClenaghan, M B (2011) Overview of common processing methods for recovery of indicator minerals from sediment and bedrock in mineral exploration. Geochemistry: Exploration, Environment, Analysis , 11(4):265 http://dx.doi.org/10.1144/1467-7873/10-IM-025

Over the past two decades, the application of indicator mineral methods to mineral exploration has expanded significantly such that they are now used to explore globally for a broad spectrum of commodities. Indicator mineral suites have been identified for a variety of ore deposit types including diamond, Au, Ni-Cu, PGE, metamorphosed volcanogenic massive sulphide, porphyry Cu, U, Sn and W. Indicator minerals, which include ore, accessory and alteration minerals, are sparse in unconsolidated sediments, thus sediment samples must be concentrated in order to recover and examine them. Because most indicator minerals have a moderate to high specific gravity, processing techniques involving density separation, in combination with sizing and magnetic separation, are used to recover them from sediment samples. This paper reviews the commonly used processing methods including panning, hydroseparation, tabling, Knelson concentrators, spiral concen- trators, dense media separators, jigs and various types of magnetic separators, as well as mineral selection and mineral chemistry determinations. Monitoring of quality control is essential at each stage in these processing, picking and analytical procedures. When reporting indicator mineral results, processing methods, fraction weights and size ranges, and laboratory name should all be recorded, in addition to indicator mineral abundance data.

Cabri LJ, Hamilton C., Hoffman E. (2011) Understanding breakage & liberation characteristics of the Bushveld UG2 Chromitite Reef using EPD. Data

McClenaghan,M. B. et al. Review of gold and platinum group element (PGE) indicator minerals methods for surficial sediment sampling. Geochemistry: Exploration, Environment, Analysis(2011),11(4):251

For gold deposits, varying combinations of gold grains, sulphides, platinum-group minerals (PGM), tellurides, scheelite and rutile, and some secondary minerals are useful indicator minerals depending on the deposit type, bedrock geology and weathering regime. Gold grain size, shape, and chemical composition for a variety of sediment types, including stream and glacial sediments, have been documented and the data used to determine potential source rocks and distance of transport. Useful indicator minerals for PGE deposits include those oxide and silicate minerals that indicate the host rocks and PGM, gold, sulphides, arsenides and antimonide minerals that indicate mineralization. Composition and morphology of PGM also have been well documented and this information is used to determine their genesis, potential source rocks and transport distance. Gold grains have been recovered from glacial and stream sediments for more than 100 years. PGM grains have a similar long history of recovery from streams, but only a few cases of recovery from glacial sediment have been reported. Research has focused on the development of microchemical characterization techniques for placer gold and PGM, while the focus for indicator minerals from glacial sediments has been the characterization of oxide and silicate suites.

Eric Wang, Fengnian Shi, Emmy Manlapig, Pre-weakening of mineral ores by high voltage pulses, In Minerals Engineering, Volume 24, Issue 5, 2011, Pages 455-462, ISSN 0892-6875, https://doi.org/10.1016/j.mineng.2010.12.011

A new comminution method has been developed by applying high voltage pulses at specific energy 1–3 kWh/t to pre-weaken mineral particles, leading to reduction in energy consumption in the downstream grinding process. Four ore samples were tested using high voltage pulses and conventional crushing in parallel for comparison. Evidence of cracks and microcracks measured with X-ray tomography and mercury porosimetry supported the principle of high voltage pulses induced damage on rocks in the electro-comminution process, which resulted in energy saving up to 24% found in this study. Ore surface texture and mineral properties affected the efficiency of high voltage pulse breakage. The feasibility of the electro-comminution and its benefits need to be investigated case by case.

Louis L. Coetzee, Salomon J. Theron, Gavin J. Martin, Juan-David van der Merwe, Tracey A. Stanek, Modern gold deportments and its application to industry, Minerals Engineering,
Volume 24, Issue 6, 2011, Pages 565-575, ISSN 0892-6875, https://doi.org/10.1016/j.mineng.2010.09.001.

Modern gold deportment studies include physical, chemical and mineralogical assessments, combined to obtain a full understanding of the nature and variability of gold in a resource. The objective is to provide information which will allow cost effective and practical processing by informing decisions regarding resource evaluation, mining method and extraction process optimization. The distribution of gold, based on speciation, grain size and mode of occurrence (liberation, exposure, and mineral association) is quantitatively determined by means of automated Scanning Electron Microscopic Techniques (QEMSCAN/MLA). Furthermore, general mineralogical characterization is undertaken in order to characterize the gangue components; with special emphasis on deleterious characteristics of the ore (e.g. cyanide consumers such as secondary Cu-species, preg-robbers/borrowers, passivation due to Sb-minerals or As-minerals and oxygen consumers such as pyrrhotite/marcasite). Predictions based on the mineralogical observations are confirmed by physical and chemical testwork. These include grading analyses, gravity separation, direct cyanidation, and diagnostic (sequential) leachtests.

Navarro-Ciurana D, Aiglsperger T, Proenza JA, (2012) PGM and Zircon in Al-rich chromitite: New insights by appling Hydroseparation technique. Macla 16, 186-187.

Accessory heavy mineral phases like Platinum Group Minerals (PGM) and zircons found within chromitites are essential for understanding the genesis and timing of ophiolite complexes. Re-Os and Pt-Os geochronometers applied to PGM and base metal sulfides have recently become indispensable tools for dating ultramafic rocks (Coggon et al., 2011 and Marchesi et al., 2011). However, Al-rich chromitites JCr/(Cr+Al)<0.6O are very poor in Platinum Group Elements (PGE). They commonly display chondrite-normalized PGE patterns typical for ophiolitic chromitites with a characteristic steep negative slope from the Ir-group (IPGE: Os, Ir and Ru) to the Pt-group (PPGE: Pt, Pd and Rh). This general PGE depletion of Al-rich chromitites can theoretically be explained by their crystallization from S-satured tholeiitic melts (Zhou et al., 1998 and Hamlyn et al., 1985). As a consequence Platinum group minerals (PGM) are rare in high-Al chromitites and reflect geochemical data by small sized (<10 Zm) Ru–Os–Ir dominated mineral phases. The dating of ophiolitic complexes is challenging as tectonic fragmentation of rocks of different ages as well as the extreme shortage of radiogenic components within ultramafic rocks (Saverlieva et al., 2007) cause a lack of concrete ages for many ophiolite massifs. Geochronical data from the Finero Massif, Western Alps, (Grieco et al., 2001) as well as the ages of the ophiolitic complexes from the Polar Urals (Saverlieva et al., 2006; 2007) were obtained by U-Pb dating of accessory zircons found withinchromitite and chromite segregations in dunite, respectively. Barring these unique chromitites from Finero, with 10-25 zircon grains (up to 600 Zm long) within a single polished section, the U-Pb dating method is limited by the general infrequency of chromitite-related zircons. Therefore, innovative concentration techniques have to be applied to achieve a sufficient number of grains for serious radiometric studies. In this work we present the preliminary results of the PGM and zircons found in HS-11 heavy mineral concentrates obtained from extremely PGE-depleted (<150 ppb total PGE) Al-rich chromitites from the Mercedita deposit, Cuba. We demonstrate how the precise hydroseparation technique HS11 can successfully be applied to challenging rock types like Al-rich chromitites, thus highlighting the great potential of this unique separation method also for geochronical studies.

Garuti, G.; Zaccarini, F.; Proenza, J.A.; Thalhammer, O.A.R.; Angeli, N. Platinum-Group Minerals in Chromitites of the Niquelândia Layered Intrusion (Central Goias, Brazil): Their Magmatic Origin and Low-Temperature Reworking during Serpentinization and Lateritic Weathering. Minerals 2012, 2, 365-384. DOI:10.3390/min2040365

A variety of platinum-group-minerals (PGM) have been found to occur associated with the chromitite and dunite layers in the Niquelândia igneous complex. Two genetically distinct populations of PGM have been identified corresponding to phases crystallized at high temperatures (primary), and others formed or modified during post-magmatic serpentinization and lateritic weathering (secondary). Primary PGM have been found in moderately serpentinized chromitite and dunite, usually included in fresh chromite grains or partially oxidized interstitial sulfides. Due to topographically controlled lateritic weathering, the silicate rocks are totally transformed to a smectite-kaolinite-garnierite-amorphous silica assemblage, while the chromite is changed into a massive aggregate of a spinel phase having low-Mg and a low Fe3+/Fe2+ ratio, intimately associated with Ti-minerals, amorphous Fe-hydroxides, goethite, hematite and magnetite. The PGM in part survive alteration, and in part are corroded as a result of deep chemical weathering. Laurite is altered to Ru-oxides or re-crystallizes together with secondary Mg-ilmenite. Other PGM, especially the Pt-Fe alloys, re-precipitate within the altered chromite together with kaolinite and Fe-hydroxides. Textural evidence suggests that re-deposition of secondary PGM took place during chromite alteration, controlled by variation of the redox conditions on a microscopic scale.

Sylvester Paul J. Use of the Mineral Liberation Analyzer (MLA) for mineralogical studies of sediments and sedimentary rocks. Mineralogical Association of Canada Short Course 42, St. John’s NL, May 2012, p. 1-16

The use of MLA in Geology, the article describes the principle of its operation and how it works. Application of the MLA to sedimentary and surficial geology but the method holds considerable promise for providing quantitative data relevant to depositional and diagenetic textures and mineralogy; porosity and permeability; sand provenance; stratigraphic correlation; lithotyping of well cuttings; till and sediment prospecting; sedimentary ore petrology; and environmental mineralogy.

Ralf O. Maxeiner, Nicole M. Rayner, Bruce M. Eglington U-Pb and Sm-Nd Isotopic Results from the La Ronge Horseshoe Project Area, Western Glennie Domain and Southern Rottenstone Domain: Evidence for 2.22 to 2.52 Ga Detritus. Summary of Investigations 2012, Volume 2.

Preliminary SHRIMP and conventional ID–TIMS U-Pb zircon analyses are reported for four samples collected from the western Reindeer Zone, as part of the Saskatchewan Geological Survey’s La Ronge Horseshoe bedrock mapping project. Two samples of feldspathic psammite from the Crew Lake assemblage, collected between Nemeiben Lake (Glennie Domain) and MacKay Lake (Rottenstone Domain), each yielded 58 zircon grains giving Paleoproterozoic to Neoarchean ages. Both gave distinct peaks at circa 1.87 Ga (60% of grains), which also represent the youngest reproducible detrital zircon ages, and broader peaks between 2.3 and 2.5 Ga, both of which compare well with age analyses obtained in a previous study of Rottenstone Domain sedimentary rocks. These results suggest that sedimentary rocks of the western Glennie Domain and eastern Rottenstone Domain have similar depositional ages of about 1.87 to 1.86 Ga, have a common history, and that their detritus was derived from mixed sources including the emerging Flin Flon–Glennie Complex and, possibly, the approaching Sask craton and/or other Archean–latest Paleoproterozoic crustal blocks within the Manikewan Ocean. Sm-Nd isotopic results are also consistent with this interpretation. The Bell Bay monzodiorite, which cuts the potassic sedimentary succession of the Crew Lake assemblage, yielded an age of 1838 ±6 Ma and an εNd value of +2.22 (T=1860 Ma). Three xenocrysts, varying in age from 1.9 to 2.4 Ga, were obtained from the monzodiorite sample and were likely derived from the sedimentary rocks. A tonalite sample collected from Nemeiben Lake contains compositionally unusual zircon grains and provided inconclusive results, suggesting crystallization ages between 1.94 and 1.84 Ga. It yielded a negative εNd value of -2.27 (T=1860 Ma) and a TDM of 2.62 Ga.

Maarten A.T.M. Broekmans; Deleterious Reactions of Aggregate With Alkalis in Concrete. Reviews in Mineralogy and Geochemistry ; 74 (1): 279–364. doi: https://doi.org/10.2138/rmg.2012.74.7

EPD allows to save heritage material after comminution. For instance, it was very helpful in studying of deleterious reactions in concrete. Authors were able to see dissolution phenomena in alkali-reactive particles in concrete liberated with EPD.

W.R. Goodall, A.R. Butcher, The use of QEMSCAN in practical gold deportment studies, Mineral Processing and Extractive Metallurgy Vol. 121, Iss. 4, 2012, https://doi.org/10.1179/1743285512Y.0000000021

Gold deportment and ore characterisation studies are key tools in gaining an appropriate understanding of complex gold ores for process development and optimisation. These studies have historically involved imprecise chemical methods with slow and costly optical microscopy for gold identification. The traditional approach requires highly skilled petrographers, is prone to human error, and is not scalable, reducing the usefulness in practical analysis. The proposed methodology utilises a decision tree and knowledge base in a staged approach to gold ore characterisation building-up progressively more detailed information about the sample mineralogy, gold deportment and key mineral properties, as the process is followed. While the automated QEMSCAN system is used for mineral and gold identification, interactive and focused data analyses are used to give more efficient and accurate results. This is complemented by smart sample preparation and chemical methods to enhance and validate the data, making the staged approach methodology reliable, scalable and therefore, practical and economical.

A. Vymazalová, F. Laufek, M. Drábek, C.J. Stanley, R.J. Baker, R. Bermejo, G. Garuti, O. Thalhammer, J.A. Proenza, F. Longo; ZACCARINIITE, RhNiAs, A NEW PLATINUM-GROUP MINERAL FROM LOMA PEGUERA, DOMINICAN REPUBLIC. The Canadian Mineralogist ; 50 (5): 1321–1329. doi: https://doi.org/10.3749/canmin.50.5.1321

A variety of platinum-group-minerals (PGM) have been found to occur associated with the chromitite and dunite layers in the Niquelândia igneous complex. Two genetically distinct populations of PGM have been identified corresponding to phases crystallized at high temperatures (primary), and others formed or modified during post-magmatic serpentinization and lateritic weathering (secondary). Primary PGM have been found in moderately serpentinized chromitite and dunite, usually included in fresh chromite grains or partially oxidized interstitial sulfides. Due to topographically controlled lateritic weathering, the silicate rocks are totally transformed to a smectite-kaolinite-garnierite-amorphous silica assemblage, while the chromite is changed into a massive aggregate of a spinel phase having low-Mg and a low Fe3+/Fe2+ ratio, intimately associated with Ti-minerals, amorphous Fe-hydroxides, goethite, hematite and magnetite. The PGM in part survive alteration, and in part are corroded as a result of deep chemical weathering. Laurite is altered to Ru-oxides or re-crystallizes together with secondary Mg-ilmenite. Other PGM, especially the Pt-Fe alloys, re-precipitate within the altered chromite together with kaolinite and Fe-hydroxides. Textural evidence suggests that re-deposition of secondary PGM took place during chromite alteration, controlled by variation of the redox conditions on a microscopic scale.

Горьковец В.Я., Рудашевский Н.С., Рудашевский В.Н., Попов М.Г., Антонов А.В. Алмазоносная диатрема лампроитов (Костомукшский рудный район, Западная Карелия) // Региональная геология и металлогения. 2012. №51. С. 79-90.

Hydroseparation provided concetrating of wide complex of diamond-indicator minerals just from 1 kg sample. Subsequent electron microprobe and optical investigation show signature of deep mantle magma source of lamproites and suggest diamond bearing nature of this diatreme in Kostomuksha ore region.

Рудашевский Н.С., Горьковец В.Я., Рудашевский В.Н., Попов М.Г., Раевская М.Б. Лампроиты Костомукшского рудного Района (Западная Карелия). 3D минералогическая характеристика // Региональная геология и металлогения. 2012. №49. С. 34-46

Two drill core samples of lamproite dikes (1.6–2.1 m in wide) were studied by means of new 3D-mineral processing technology: crushing of the rocks, screening and hydroseparation (HS) the heavy mineral concentrates (40–250 m), mounted in polished sections with some hand-picking; all these products as well as polished sections of rocks were characterized by scanning electron microscopy and microprobe analyses. The samples represent as lamproites are located in magnetite quartzites, quartz-feldspar-biotite and carbonaceous shales; in komatiites. The chemical compositions of the both samples are typical for lamproites. The first sample is extensively replaced by secondary saponite and calcite sanidine-amphibol-phlogopite basic lamproite; the second sample is extensively replaced too (serpentine, calcite) olivine-diopside-phlogopite ultrabasic lamproite. In the HS concentrates numerous accessories containing Ti, P, Ba, Sr, Zr, TR, and Nb were identified. Both samples contained mantle-source xenocrystals of peridotites and rocks of metamorphic basement: chromium-diopside, high-Cr pyrope, chromium spinels (up to 66.5 wt. % Cr2O3), picroilmenite and geikielite, corundum, almandine. The difference in mineral composition between these two lamproites, is obviously due to contamination of the rocks of the side walls of the dyke by matrix magma. Lamproites as well as kimberlites of the Fenno-Karelian province represent new potential source of Russian diamonds.

Osbahr, I., Klemd, R., Oberthür, T. et al. (2013) Platinum-group element distribution in base-metal sulfides of the Merensky Reef from the eastern and western Bushveld Complex, South Africa. Miner Deposita 48:211. https://doi.org/10.1007/s00126-012-0413-8

Base-metal sulfides in magmatic Ni-Cu-PGE deposits are important carriers of platinum-group elements (PGE). The distribution and concentrations of PGE in pentlandite, pyrrhotite, chalcopyrite, and pyrite were determined in samples from the mineralized portion of four Merensky Reef intersections from the eastern and western Bushveld Complex. Electron microprobe analysis was used for major elements, and in situ laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) for trace elements (PGE, Ag, and Au). Whole rock trace element analyses were performed on representative samples to obtain mineralogical balances. In Merensky Reef samples from the western Bushveld, both Pt and Pd are mainly concentrated in the upper chromitite stringer and its immediate vicinity. Samples from the eastern Bushveld reveal more complex distribution patterns. In situ LA-ICP-MS analyses of PGE in sulfides reveal that pentlandite carries distinctly elevated PGE contents, whereas pyrrhotite and chalcopyrite only contain very low PGE concentrations. Pentlandite is the principal host of Pd and Rh in the ores. Palladium and Rh concentrations in pentlandite reach up to 700 and 130 ppm, respectively, in the samples from the eastern Bushveld, and up to 1,750 ppm Pd and up to 1,000 ppm Rh in samples from the western Bushveld. Only traces of Pt are present in the base-metal sulfides (BMS). Pyrrhotite contains signify cant though generally low amounts of Ru, Os, and Ir, but hardly any Pd or Rh. Chalcopyrite contains most of the Ag but carries only extremely low PGE concentrations. Mass balance calculations performed on the Merensky Reef samples reveal that in general, pentlandite in the feldspathic pyroxenite and the pegmatoidal feldspathic pyroxenite hosts up to 100 % of the Pd and Rh and smaller amounts (10–40 %) of the Os, Ir, and Ru. Chalcopyrite and pyrrhotite usually contain less than 10 % of the whole rock PGE. The remaining PGE concentrations, and especially most of the Pt (up to 100 %), are present in the form of discrete platinum-group minerals such as cooperite/braggite, sperrylite, moncheite, and isoferroplatinum. Distribution patterns of whole rock Cu, Ni, and S versus whole rock Pd and Pt show commonly distinct offsets. The general sequence of “offset patterns” of PGE and BMS maxima, in the order from bottom to top, is Pd in pentlandite→Pd in whole rock→(Cu, Ni, and S). The relationship is not that straightforward in general; some of the reef sequences studied only partially show similar trends or are more complex. In general, however, the highest Pd concentrations in pentlandite appear to be related to the earliest, volumetrically rather small sulfide liquids at the base of the Merensky Reef sequence. A possible explanation for the offset patterns may be Rayleigh fractionation.

Jan Pašava, Federica Zaccarini, Thomas Aiglsperger , Anna Vymazalová Platinum-group elements (PGE) and their principal carriers in metal-rich black shales: an overview with a new data from Mo-Ni-PGE black shales (Zunyi region, Guizhou Province, south China) Journal of Geosciences, volume 58 (2013), issue 3, 209 - 216 DOI: http://dx.doi.org/10.3190/jgeosci.147

Lower Cambrian Mo–Ni sulfidic black shales from the Huangjiawan mine (Guizhou Province, south China) have anoma- lous platinum-group elements (PGE) concentrations (up to ~1 ppm in total). In order to identify principal PGE carriers, we used heavy mineral separates which were produced by innovative hydroseparation techniques. Subsequent detailed mineralogical study using electron microprobe did not result in the identification of discrete platinum-group minerals. Pyrite (grainy, not framboidal), millerite and gersdorffite that were found in our heavy concentrate were analyzed for PGE and Re. We found that they contain the following concentrations of PGE and Re: pyrite (up to 490 ppm Pt, 390 ppm Pd and 220 ppm Rh), millerite (up to 530 ppm Pt, 430 ppm Pd and 190 ppm Rh) and gersdorffite (up to 410 ppm Pt and 320 ppm Pd; no Rh detected). Rhenium was detected only in grainy pyrite (up to 1060 ppm). It was found that despite anomalous PGE concentrations, the Mo–Ni black shales do not contain any platinum-group minerals and that the PGE are bound to pyrite and Ni-sulfides (millerite and gersdorffite).

Oberthür, T., Melcher, F. Buchholz, P. & Locmelis, M. (2013) The oxidized ores of the Main Sulphide Zone, Great Dyke, Zimbabwe: Turning resources into minable reserves-mineralogy is the key. Platinum 2012. Southern African Institute of Mining and Metallurgy, 647-672.

The Great Dyke of Zimbabwe constitutes the world’s second largest reserve of platinum group elements (PGE) after the Bushveld Complex in neighbouring South Africa. Within the Great Dyke, economic concentrations of PGE are restricted to sulphide disseminations of the Main Sulphide Zone (MSZ), which are currently mined at the Ngezi, Unki, and Mimosa mines. Near-surface oxidized MSZ ores have a large potential. Their total resources are in the range of 160–250 Mt; however, all previous attempts to extract the PGE from this ore type have proved uneconomic due to low PGE recoveries (<< 50 per cent) achieved by conventional metallurgical methods. Within the ores of pristine, sulphide-bearing MSZ, the PGE are bimodally distributed. Platinum occurs mainly in the form of discrete platinum group mineral (PGM) grains (mainly bismuthotellurides, sulphides, and arsenides), whereas approximately 80 per cent of the Pd (and some Rh) is hosted in pentlandite. Within the oxidized MSZ ores, the PGE are polymodally distributed. Whereas the arsenide- and sulphide-PGMs that make up approximately 25 per cent of the original Pt content of the ore largely remain stable (relict PGMs), the remaining PGMs are disintegrated. The base metal sulphides are destroyed, partly releasing their base metal and PGE contents, and are replaced by iron oxides or hydroxides. Unspecified amounts of the PGE are redistributed and either form secondary PGMs, are found in chemically and mineralogically ill-defined (Pt/Pd)-oxides or hydroxides, or in iron-hydroxides, Mn–Co-hydroxides, and in secondary silicates. The problematic processing of oxidized MSZ ores is attributable to their complex nature and polymodal distribution of the PGE, prohibiting a significant upgrading of the ores by conventional metallurgical methods. Therefore, only bulk leaching methods are viable for ore treatment, and novel metallurgical methods have to be developed for the processing of these ores. Our ongoing work aims at locating the PGE in their mineralogical form in order to understand the mineralogical balance of the PGE in the ores and thereby facilitate the evaluation of metallurgical options for their recovery. A short overview on options and recent advances regarding the recovery of the PGE from oxidized ores is given.

Klaas Peter van der Wielen, Richard Pascoe, Alex Weh, Frances Wall, Gavyn Rollinson, The influence of equipment settings and rock properties on high voltage breakage, In Minerals Engineering, Volumes 46–47, 2013, Pages 100-111, ISSN 0892-6875, https://doi.org/10.1016/j.mineng.2013.02.008

High voltage breakage is a novel comminution method that relies on highly energetic electrical pulses to weaken or fully fragment rocks. The potential of this technology to improve liberation and increase the grindability of ores has been demonstrated previously, but the fragmentation process is not fully understood. In this study a total of 20 rock types were treated in a SELFRAG Lab device to determine the influence of equipment parameters on breakage. Rock mass properties and Bond Work Index were determined for each rock type to identify their relation to breakage behaviour. Results show how, by influencing total applied energy, the number of discharges and voltage are the two major influences on the resultant product size. It has also been shown that coarser feed sizes are more amenable to high voltage breakage. Acoustic impedance, porosity and quartz content were found to relate to breakage but Bond Work Index only correlates loosely.

Thomas Oberthür, Frank Melcher, Malte Junge, Marek Locmelis, Peter Buchholz, Herwig Marbler, Dennis Kraemer, Gila Merschel, and Michael Bau, 2013 The oxidized ores of the Main Sulphide Zone, Great Dyke, Zimbabwe: Turning resources into minable reserves-mineralogy is the key. South African Institute of Mining and Metallurgy 113(3):191-209 (Presentation)

Alireza Eslami, Majid Ghaderi, Amir Morteza Azimzadeh (2013) Innovative applications of electric pulse disaggregation and hydro-separation techniques in the exploration of platinum group elements in the Zagros ophiolites. 1st International Congress on Zagros Orogen, At Shahid Beheshti University, Tehran, Iran

The Upper Cretaceous Zagros ophiolites of Iran host a significant number of chromitite deposits and occurrences. Platinum Group Element (PGE) anomalies have been previously reported; however, the available data on the PGE mineralization are scarce. Large chromitite pods and residual to cumulate dunitic lenses are restricted to the outer Zagros Neyriz and Haji–Abad ophiolites with a harzburgite-dominant mantle, because they have undergone a higher degree of partial melting than others with lherzolite-dominant mantle. Very little information is available concerning the distribution and mineralogy of PGE in the Zagros ophiolites. Novel mechanical separation techniques [Electric Pulse Disaggregation (EPD) and Hydro-Separation (HS)] therefore, should provide a more complete picture of PGE mineralogy in chromitites. In addition, in-situ investigations of polished sections provide more adequate information on the primary or secondary origin for Platinum Group Minerals (PGM), based on their textural position in the chromitites. Both methods are complementary and must be used jointly in order to precisely determine the distribution of PGM in Zagros chromitites. We propose accurate PGE mineralogical studies of Upper Cretaceous Zagros ophiolites by combining in-situ investigation in polished sections and mechanical separation (HS or EPD with HS).