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103 Igneous Rock Teaching Collection: Room 325A McCone Hall
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Note: There are thin sections for each sample also stored in room 325A
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Spec #Petrog. NameMineral CompositionStructures, Textures, Facies, Etc.LocalityRemarksThin Section Only
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103-1Andesite, ScoriaceousInclusions of tuff and/or altered feldspar (25%), limonite in some vesicles, altered biotite phenocrysts (10%), altered
hornblende or augite (5%)
Porphyritic, vesicular with aphanitic groundmass, weatheredUnknown
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103-3Tuff, rhyolitic lapilliPumice (80%), lithic fragments (15%), biotite and/or hornblende (5%)Pyroclastic, massive, lapilli size, lithicWest side of lower Sacremento Valley (taken from material used as road fill south of Vacaville), Sacramento Valley, Calif.
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103-4Tuff, crystal lithicQuartz (15%), biotite (5-10%), lithic fragments (20%), plagioclase (10%), tuffaceous matrix (50%)Pyroclastic, ash to lapilli, massive; probably water-laidPine Nut Range, Nevada
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103-7Basalt, amygdaloidalCalcite in vesicles (15%), altered augite? (15%), quartz (less than 5%), groundmass (60%)Porphyritic with aphanitic groundmassHoughton Co., MichiganTermed "Amygdaloidal Diabase" by Wards
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103-8Granite, v. LuxullianitePink orthoclase with good Carlsbad twinning, quartz, radiating tourmalineSomewhat spheruliticLuxullian, Cornwall, England
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103-9Basalt: AugiteAugite phenocrysts, no olivine (accord. to H. W.), amygdules of carbonate and chlorite, groundmass probably indeterminate in hand specimen consists of microcrystalline plagioclase, augite, clinozoisite, sphene, and minor amounts of brown hornblende.Porphyritic with micro-crystalline groundmass, Phenocrysts are medium-grained & compose 50% of rockIn place, 2-4' wide dike in stream bed near where road crosses creek, S. central portion Sec. 35, T6N, R10E, Sutter Creek Quad., Calif.Probably dike of Logtown Ridge Andesite
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103-12Rhyolite: BiotiteOrthoclase (10%), quartz (5%), biotite (5%)Porphyritic, with microcrystalline groundmass. Phenocrysts constitute 20% of rockDevil's Gate, Hwy 395, Bridgeport Quad., Calif.Cannot locate area-SFJ 3/70
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103-13Andesite: HornblendePhenocrysts: hornblende (40-50%), plagioclase (40-50%). Amygdules: clinozoisite?, plagioclase (5%), chlorite, epidote. Hornblende needles in groundmass.Porphyritic with fine-grained to microcrystalline groundmass. Phenocrysts up to 4mm long (minor poikilitic texture with hornblende in plagioclase).2 miles NW of Volcano, Jackson Quad., Calif.
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103-14Andesite: Biotite, hornblendePhenocrysts: plagioclase, hornblende, biotite, orthoclase?, quartz (rare)Porphyritic, microcrystalline groundmassFrom well cores, S. side of Marysville Buttes (see map in Williams' U.C. publication on Marysville Buttes), Calif.
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103-15Welded tuff, RhyoliticColorless glass shard (90-95%) includes some pumice fragments; orthoclase (5%±), plagioclase (trace), biotite (trace), quartz (1-2%), lithic fragments (minor--old sed. & volcanic rocks?), opaque matter (1-2%) - indeterminate.Pyroclastic, ash to lapilli size fragments. Some (5-7%) non-vitric material. Fragments have somewhat flattened appearance & rock is well compacted. Lapilli to 2 to 3mm or more. Mostly vitroclastic.Hwy 20 near junction with Hwy 40, below Emigrant Gap, Calif.Cannot locate area-SFJ 9/71
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103-16Rhyolite: BiotitePhenocrysts; plagioclase (all large phenocrysts and almost all of groundmass, twinning poor); NO orthoclase; biotite (5%, partly altered); quartz (none in ts, probably in groundmass and is visible as phenocrysts in hand specimens).Porphyritic w/ micro-crystalline groundmass (aphanitic w/ handlens). Phenocrysts total 10-15% of rock, but few attain 2-3mm, so that a figure of less than 10% will probably be given. The small plag. laths in groundmass have trachytic structure not visible with handlens. Banded.South side of Sutter (Marysville) Buttes, Calif.
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103-17Rhyolite: BiotitePhenocrysts (10% of rock) average approx. 1mm; essen. min.: plagioclase (60%-sharply euhedral), quartz (5%, subhedral); char. min. acces.: biotite (35%, euhedral grains); minor acces. min.: epidote (easily visible w/ hand lens, grains up to 1mm long), apatite (euhedral stubby grains difficult to see with hand lens, but some 1mm)Porphyritic, aphanitic-microcrystalline groundmass. Color: lavenderSouth side of Sutter (Marysville) Buttes, Calif.
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103-18Quartz diorite: Biotite-hornblende-pyroxenePlagioclase 60-65%, quartz 15-20%, biotite 4-5%, hornblende (replacing augite) 10-25%, hypersthene 9-10%, augite 2-3%.Holocrystalline, phanerocrystalline, allotriomorphorphic granular, medium grainedSecured from plant at Rocklin, Calif. Said to have come from a quarry on the American River, Sierra Nevada, Calif.
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103-19Granite, Alkali, pinkQuartz 25%, microcline 40%, albite 35%, hornblende, biotite, muscovite; minor min: magnetite 1%Allotriomorphic granular, medium grainedGranite Mountain, MissouriSupply secured at plant of Rocklin Quarries, Calif.
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103-20Gabbro, Saussuritizied hornblendePlagioclase (40%, saussuritized), hornblende ("60%", developed by uralitization of pyroxene), pyroxene (trace, remnant); minor access. min.: sphene (trace), magnetite (devel. as a result of alteration of hornblende to chlorite); second. min.: chlorite (fully half of the hornblende has been altered to chlorite)Holocrystalline, phanerocrystalline, allotriomorphorphic granular, medium grainedLarge boulders downstream from outcrop where road crosses creek in south central portion Sec. 35, T6N, R10E, Sutter Creek Quad., Calif.
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103-21 placed behnd 103-46Quartz diorite: Saussuritized hornblendePlagioclase (saussuritized), hornblende (poikilitic)On road near Bear River Bridge, near Colfax on Colfax-Grass Valley road, near Colfax, Calif.Cannot locate area-SFJ 9/71
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103-22ObsidianUnknown
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103-26Gabbro, Saussuritized porphyriticAugite (35%, phenocrysts 1-10mm, partly uralitized), plagioclase (10-20%, saussuritized, up to 3mm, may be chloritized); groundmass: saussuritized plagioclase, chlorite, ilmenite, apatite, augitePorphyritic with microcrystalline or aphanitic groundmass, saussuritizedFrom large boulders, downstream from outcrop area, at point where road crosses creek. Surface flows and dikes, or plutonic intrusives (batholiths, stocks, etc.). South central Sec. 35, T6N, R10E, Sutter Creek Quad., Calif.
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103-30GranodioriteAndesine to oligoclase (58%), quartz (20%), biotite (10%, chloritized), muscovite (2%), orthoclase (10%?, interstitial), epidote (trace-F. J. Turner), chlorite after biotite.Hypidiomorphic-granular, medium-grainedRocklin Quarries, Calif.
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103-32SerpentineSerpophite, chrysotile, calcite, chromiteOn road between Nevada City and Grass Valley, Calif.See W.T. & G., p.83-84 for "serpophite" Cannot locate area-SFJ 9/71
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103-33BasaltPhenocrysts: plagioclase (1mm), augite (very small grains, less than 0.05mm). Green alteration may be from olivine, but very few shapes left. Magnetite, calcite, chlorite, pigeonite (virtually uniaxial).Porphyritic, micro-crystalline groundmassBerkeley Hills, Calif
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103-35Rhyodacite PorphyryPhenocrysts: plagioclase (sericitized), orthoclase (altered) (orthoclase/plagioclase ratio 1:2), embayed quartz. Groundmass is all quartz and K-feldspar . Original hornblende is now completely replaced by chlorite, sericite, and magnetite. Acces. apatite.Porphyritic, micro-crystalline groundmassPine Nut Range, Nevada
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103-36Quartz Monzonite, PorphyriticPlagioclase (40%), orthoclase (305), quartz (20%), hornblende (10%), magnetite, sphene, hematite, chloriteHypidiomorphic granular, medium-grainedPine Nut Range, Nevada
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103-37Olivine Basalt, AlteredPlagioclase phenocrysts to 2mm; groundmass of plagioclase, pyroxene, and completely altered olivine (chlorite or serpentine). Few quartz grains with reaction rims of pyroxene.Porphyritic, micro-crystalline groundmassBerkeley Hills, Calif
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103-38Laurvigite: (Larvikite; syenite)Soda-orthoclase/oligoclase; mafics: titanaugite, Ti-rich biotite, hornblende (trace), magnetite or ilmenite, apatite, marcasite or pyrite. Oligoclase and soda-orthoclase in intimate intergrowth create schillerized phenocrysts; anti-perthitic.Allotriomorphic, coase-grainedSweden-supply secured at plant of Rocklin Quarries, Calif.; trade name of this imported building stone is "Emerald Pearl".
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103-39Andesite: Hornblende, pyroxeneHornblende (oxidized slightly, reddish in ts. Many show alteration of core), plagioclase, augite (hornblende/augite = 3/1). Can be distinguished with handlens, poor cleavage, stubby, green in small xls., black in large, no reddish color, some yellow-brown). Tridymite in druses.Porphyritic, micro-crystalline groundmassEbbets Pass, Sierra Nevada, Calif.Could not locate. Too indefinite-SFJ 6/66
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103-41Norite: HornblendeHornblende replacing hypersthene, some antigorite? after hypersthene, ilmenite, augite, and biotite. Plagioclase 60%, amphibole 35%, magnetite-apatite-crud 5%, some biotite, pyroxene (hypersthene to augite = 3/1).Hypidiomorphic granular, medium-grainedSalem, Essex Co., MassachusettsWard's description; hornblende diorite
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103-43Perlite; SpheruliticPerlitic glass with rare phenocrysts; quartz, plagioclase, biotite, orthoclase(?)Perlitite; spherulitic porphyritic with perlitic holohyaline groundmassQuarry to west of town of Shoshone, Calif. (need 4-wheel drive from Shoshone); prospect on map near NE corner Sec. 35, T22N, R6E, Shoshone Quad., 1:62500. 1951, Calif.Loc. OK-SFJ 3/68
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103-44 Not in order, behind 103-21 and in front of 103-49Norite, UralitizedPlagioclase (60%), pyroxene (largely uralitized augite and hypersthene), hornblende (35%, replacing pyroxenes), biotite (rims on ilmenite), ilmenite, chlorite?Note uralization of pyroxenesSupply secured from plant at Rocklin Quarries, Calif., but said to have come from near Escondido, San Diego Co., Calif.
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103-46Tuff; Rhyolitic, vitricGlass shards (90-95%), ferromagnesians (5-10%), lithic fragments (1%)Pyroclastic, massive, fine ashReese River, 58 miles toward Austin from Battle Mtn., Nevada
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103-49Rhyolite, porphyriticQuartz (25%), orthoclase (55%), hornblende, biotite (altered to chlorite), pyrite, calcitePorphyritic, micro-crystalline groundmassUnknown
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103-50GranodioritePlagioclase (55%), quartz (25%), biotite (10%), muscovite (5%); perthite + microcline + orthoclase (5%); chlorite, apatite, sphene, epidote (trace).Hypidiomorphic granular, medium-grainedWoodbury, Vermont(Wards: Biotite granite or quartz monzonite)
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103-53Leucitophyre (Leucite phonolite)Leucite; Leucite phenocrysts (30%), plagioclase phen. (3%), augite phen. (5%); groundmass (60%): sanidine (40%), biotite (8%), augite (11%), occuring in vesicles (seen only with hand lens) are vonsenite, (Mg, Fe2)2 Fe3BO5. (see Remarks)Porphyritic, micro-crystalline groundmassCivita Castellana, Latium, ItalyThe vonsenite was identified by Prof. Pabst (Dec. 1964). Vonsenite is found in certain skarns, but it has not been noted previously in volcanic rock. See attached note on X-Ray data (on back)
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103-54Leucitophyre (Leucite phonolite)Phenocrysts: leucite with polysynthetic twinning, embayed dark bordered nosean, zoned aegirine-augite, melanite garnet. Groundmass: sanidine, aegirine-augitePorphyriticProbably Rieden, Eifel, Germany
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103-57Syenite: Nepheline (Litchfieldite)Orthoclase = microcline (25%), albite (50%), nepheline (15%), lepidomelane (7%), cancrinite (2%), sodalite, spheneLitchfield, Maine
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103-61Granodiorite, HornblendePlagioclase (40%), quartz (20%), orthoclase (5%?), hornblende (25%), biotite (10%), chlorite, apatiteHypidiomorphic granular, medium-grained. Faint linear structure.Unknown
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103-74Basalt, OlivinePlagioclase (30%), augite (15%), olivine (15%); groundmass (40%)Dense, massive, porphyritic with aphanitic groundmassFrench Ranch, Fruto Quad., Calif. Willows-Chico area
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103-88Rhyolite, BiotitePhenocrysts: blue quartz, plagioclase to orthoclase, biotitePorphyritic, microcrystalline groundmassButte, Montana
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103-104Quartz MonzoniteOrthoclase (35%), plagioclase (35%), quartz (20%), biotite (10%)Hypidiomorphic granular, medium-grained. Faint linear structure.Hetch Hetchy, Lake Eleanor Quad., Calif. Station 526-30 in new North Mountain Tunnel, Hetch Hetchy Water ProjectSupercedes old 103-104, discarded because of insufficient specimens.
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103-114Porphyry, QuartzGreen Monster Prospect, south of Jerome, Arizona
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103-119Quartz MonzoniteQuartz (35%), orthoclase (20%), plagioclase (35%), biotite (10%), hornblendeSubporphyritic, somewhat weathered with hypidiomorphic granular groundmassUnknown
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103-122Andesite, HornblendeHornblende phenocrysts, 15%; groundmass: hornblende, 25% (of rock); plagioclase, 60% (ext. angle 22° to fast direction), some epidote developing from plagioclase groundmass. Phenocrysts to 2.5mm; very fine-grained groundmass.Dike in granodiorite: hornblende phenocrysts oriented vertical, parallel to dike walls. Porphyritic with microcrystalline groundmass.Coffee Creek, Trinity Co., Calif.Locality indefinite; could not locate, 8/70 SFJ
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103-123Serpentine, Massive (JF)Serpentine (85%, alteration of hornblende), plagioclase (5%, altered), prehnite (5%, lighter green area, highly brecciated), chlorite, sphene.Sheared hornblendite? Holocrystalline (?), allotriomorphic, granular, medium-grained; autobrecciated. Microbrecciated to great extent.Quarry at road junction, E. side of Tiburon Peninsula, Calif. 750' SE of letter "N" in Tiburon, T1N, R6W, San Quentin Quad., 1:24000, 1959, Calif.
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103-136Andesite porphyry: SaussuritizedPhenocrysts: plagioclase (saussuritized), augite (rare); groundmass: plagioclase (partly saussuritized), augitePorphyritic, with microcrystalline groundmassApplegate Creek, Central Pacific R.R., Calif.
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103-142Pumice, RhyoliteMono Craters, Calif?
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103-150ApliteQuartz (30%), plagioclase (oligoclase 10%), orthoclase + microcline (55%), biotite (5%), sphene (minor).Dike cutting schist; allotrimorphic-granular, fine-grainedMarkleeville, Calif.Loc. too indefinite; could not locate- SFJ 6/66
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103-154DiabaseMedium-grainedJersey City, N.J.
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103-165Basalt: AmygdaloidalPlagioclase with augite and olivine in a groundmass of brown glass, chlorite, and opaques. Amygdules contain zeolites, chalcedony, and chloritic material (?)Amygdaloidal, hyalo-ophitic textureBerkeley Hills, Calif
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103-166SerpentineHighly sheared and slickensidedArlington Ave. at El Cerrito city limits, Calif.
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103-167Basalt, OlivinePhenocrysts: plagioclase (to 3mm), olivine (to 1mm, partly chloritized). Groundmass: augite, plagiocalse, magnetitePorphyritic, microcrystalline groundmassSkyline Blvd. at S end of Grizzly Peak, roadcut on Grizzly Peak Blvd., Berkeley Hills Briones Valley Quad., 1:24000, 1958, Calif.
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103-168Basalt, AugitePhenocrysts of plagioclase and augite, opaques, in groundmass of altered plagioclase and magnetitePorphyriticSkyline Blvd. at pass, Berkeley Hills, Calif.
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103-170GabbroPlagioclase (An50?) 45%, augite (2V = 45. opt.+), hypersthene (red-green pleo.), olivine-trace, grn. biotite(?) altn. with opaques, in augite, little chlorite.Allotrimorphic-granular, medium grainedEast Sooke Peninsula, S. Vancouver Island, British Columbia, CanadaB.C. Dept. Mines stock for Prospectors' sets
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103-171Pulaskite: (Syenite)Orthoclase (80%), biotite (10%), plagioclase (5%), augite (5%, altering to chlorite)Panidiomorphic-granular coarse-grainedYmir, SE British Columbia, CanadaDescribed as "Pulaskite" in Geol. Surv. Canada Report
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103-174Quartz DioritePlagioclase (60%), quartz (15%), hornblende (20%), biotite (5%), epidote (minor)Hypidiomorphic-granular, coarse-grainedUnknown
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103-175DacitePhenocrysts: zoned plagioclase, quartz, brown biotite (interesting poikilitic texture with plagioclase, small xls-laths growing parallel to 001 cleavage of biotite), oxyhornblende with magnetite rims, scattered magnetite (?). Groundmass: abundant small plagioclase laths, devitr. volc. glass?Porphyritic with microcrystalline groundmass. Phenocrysts euhedral 1/2 mm to 3 or 4 mmFulton's Quarry, Reno, Nevada
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103-179Granodiorite: HornblendePlagioclase (65%), orthoclase (5% - difficult to determine with hand lens), quartz (15%); charac. min.: hornblende + biotite (15-20%, intimately intergrown, hornblende in excess). Minor; allanite (1%), sphene, magnetite. Secondary: chlorite (developing from biotite and hornblende)Hypidiomorphic-granular, coarse-grainedMoss Beach, Calif.
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103-183Granite, Red microclineRed microcline-perthite, quartz, albite, biotite, muscovite, and minor tourmaline (F. J. T.)Hypidiomorphic-granular, coarse-grainedSweden-purchased by South San Francisco plant of Calif. Cut Stone Granite Works.Trade name: "Imperial Red"
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103-184Ganite, Alkali (Aegirine-riebeckite)Quartz (20-25%), orthoclase (65-70%, probably largely anorthoclase partly exsolved); riebeckite (large xls & microxls orientated w/in orthoclase, bluish green, riebeckite, though toward margins of riebeckite); sphene, allanite, magnetite, garnet.Hypidiomorphic-granular, medium-grainedQuincy, Mass. Secured from South S. F. plant of Calif. Cut Stone Granite Works.
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103-186Quartz Monzonite, BiotiteBiotite; Quartz 35%, orthoclase & plagioclase 50-55% (exact ratio of these minerals is impossible to determine withoutwork, but it appears that the plagioclase equals or exceeds orthoclase), biotite 10-15%, magnetite, and sphene (trace).Hypidiomorphic-granular, fine-grainedSecured from South San Francisco plant of Calif. Cut Stone Granite works. Said to come from near Porterville, Calif.
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103-194Phonolite, NephelineNepheline (30%), aegirine-augite (5%), sphene (trace). Zeolites can be seen under microscope in druzes.Porphyritic with glassy groundmass. 60-65% coarse-grained phenocrysts to 5mm.Central crater of Sadiman Volcano, just west of Ngorongoro Crater, Tanzania, Africa
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103-198Andesite, Biotite-hornblendeZoned plagioclase phenocrysts, oxy-hornblende with magnetite rims, brown biotite; magnetite partly oxidized; most of groundmass consists of plagioclase laths showing poorly developed trachytic structurePoorly developed trachytic structureWolkenburg, Siebengebirge, W. Germany
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103-199Trachyte: Riebeckite (H. Williams)*Phenocrysts (30%): Sanidine (20%, neg. relief, low), riebeckite (10%, highly pleochroic blue-green to yellow, low polarizing high relief). Groundmass: sanidine (65%, carlsbad twinning, low neg relief), analcite (?, 5%, high neg relief, isotropic)Porphyritic with a microcrystalline groundmass.Hohenburg, Berkum on Rhine, W. Germany*Labeled rhyolite-liparite on German label
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103-200Quartz DioritePlagioclase (50%, partly saussuritized), quartz (15%), hornblende (25%), biotite (10%)Hypidiomorphic-granular, medium-grainedUnknown
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103-201Rhyolite, BiotiteBiotite phenocrysts in fine-grained groundmassRockland Canyon, Pine Grove Quad., Nevada6.5x10^6 years old: KA sample KA 2436, reported in GSA Bull. vol. 84, pp.2489-2510, 1973
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103-202Andesite: Biotite-hornblende-augitePhenocrysts: plagioclase, sanidine, augite. Groundmass: 65% microlites of feldspar and magnetite, 5% oxyhornblende (magnetite rimmed) and oxybiotite (rimmed with magnetite). Minor:some tridymite lining cavities.Fine-grained porphyritic with an aphanitic groundmass. Phenocrysts are mostly between 1/2 and 1 mm (largest is 12 mm)Stenzelberg, Siebengebirge, Germany
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103-204Quartz diorite: Hornblende, biotite (H.W.)Plagioclase (55%), quartz (10%), hornblende (20%), biotite (15%), magnetite (2%), pyrite.Hypidiomorphic (?) granular, fine to medium-grained. Holocrystalline, phanerocrtstallineUnknownTonalite
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103-207Basalt, OlivinePhenocrysts (15%): olivine (10%, with iddingsite alteration), plagioclase (5%). Groundmass (85%): plagioclase (45%), augite (40%, intergranular between euhedral plagioclase). Iron ore (2%).Porphyritic with a fine-grained, pilotaxitic or trachytic groundmass"Basalt" block quarry on Capt. J. McDonalds Ranch, E of Santa Rosa, Calif.
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103-208DiotirteBlack and whiteLos Angeles Co., Calif.
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103-216GraniteQuartz (50%), alkali feldspar (40%, mostly orthoclase but a good deal of altered albitic plagioclase), biotite (5%, altered to chlorite in part), muscovite (less than 5%), sphene (trace)Allotriomorphic-granular, medium-grainedSilesia
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103-225Hornblende DioriteHornblende, plagioclase, hypersthene?, magnetite, biotite (trace).Salem, Mass.
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103-226Quartz Diorite, BiotitePlagioclase (60%), quartz (10%), biotite (20-25%), pyroxene (5%+, hypersthene & augite show diallage parting), hornblende (trace, alteration of pyroxene), apatite (1%, rods in biotite xls. & stubby xls in groundmass), sphene (trace), pyrite (trace), magnetite (abundant but easily visible only on polished faces)Holocrystalline, hypidiomorphic, medium-grained, Schiller in augite and hyperstheneSouth America (probably Chile)- secured from S. F. plant of Vermont Marble Co. Trade name "Black Andes"
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103-227Basalt, OlivinePhenocrysts: olivine, augite, plagioclase; groundmass: plagioclase laths with intergranular augite, olivine, and opaques.Porphyritic with groundmass plagioclase showing a sub-parallel alignment of laths (pilotaxitic texture)Bradbury Well, W of Shoshone, N central part of Avawatz Mtns. Quad., Calif.
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103-230Tuff: Rhyolitic, vitric-crystal-lapilliBiotiteVitric-crystal-lapilliPine Grove Hills, near Pine Grove, Nevada
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103-241GabbroBytownite (about 95%), minor mafics, (could be called "bytownitite")Medium to coarse-grainedDuluth, Minn.
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103-242Porphyry, FelsiteSanidine; Phenocrysts (30%): plagioclase (15%), sanidine (10%), quartz (5%); groundmass (70%): quartz-feldspar intergrowthsPorphyritic with an aphanitic groundmassBasalt Rock Co. quarries SE of Napa, Calif.
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103-258Tuff, Lithic-lapilliLithic fragments (35%), plagioclase and quartz xls (30%), tuffaceous matrix (35%)Pyroclastic, lapilli size. Multi-coloredCalifornia?
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103-262ScoriaGroundmass (90%), feldspar phenocrysts (10%)Oxidized scoriaceousBsalt Rock Co. Quarries, SE of Napa, Calif.
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103-263BasaltFeldspar (45%, a few xls as phenocrysts), augite (30%, a few xls as phenocrysts), opaques (25%, magnetite?)Plagioclase laths strongly aligned (trachytic texture), augite & opaques are concentrated into alternating bands. The rock is mostly microcline but a few phenocrysts of plagioclase and augite are present.Basalt Rock Co. quarries SE of Napa, Calif.
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103-264VitrophyrePerlitic volcanic glass with phenocrysts of plagioclase (35%), olivine (a few small phenocrysts), pyroxene?Porphyritic with a perlitic glassy groundmassBasalt Rock Co. quarries SE of Napa, Calif.
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103-265Andesite, HornblendeHornblende, biotite, plagioclasePorphyritic with aphanitic groundmass. Brecciated with angular fragments in a similar matrixJackson Butte, Mokelumne Hill Quad., Calif.Intrusive auto-breccia
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103-266 & 266ASerpentineHwy 70 (89) between Quincy and Blairsden, about 3/4 mi. W-NW of underpass which is near center of Sec. 25, T24N, R10E, Quincy Quad., 1:62500, Calif.Loc. OK-SFJ 8/70
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103-267 In the excel doc but not in physical fileDioriteHornblende (saussuritized gabbro); Hornblende, plagioclase, clinozoisite
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103-268Serpentine, AntigoriteBastite crystals partly replaced by antigorite in an antigorite matrix (F. J. Turner).About 100 yds. E of the RR underpass, on back towards RR, Hwy 89, between Quincy and Blairsden, at center of Sec. 25, T24N, R10E, Quincy Quad., Calif.
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103-269Basalt, OlivinePhenocrysts: plagioclase and olivine (altered to iddingsite in part). Groundmass: plagioclase.Porphyritic with microcrystalline groundmass.1.2 miles from edge of Susanville, on Hwy. towards Chester, Calif.Cannot locate area-SFJ 7/70
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103-275Syenite: BarkevikiteBarkevikite; Clinozoisite?, prehniteHypidiomorphic-granular, medium grainedFrom large blocks in stream at road crossing just N. of center of S. line. Sec. 25 (containing beniotite "Gem Mine"), T18S, R12E, New Idria, Calif.
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103-278Volcanic Breccia: (Prob. dacitic/andesitic)Plagioclase and mafics are wholly altered (replaced by chalcedony, calcite, phyllosilicate). Silica cement (crypto- to micro-crystalline quartz).Checked by R. L. Hay 1980
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103-279Pegmatite, TourmalineTourmaline, quartz, K-feldspar, plagioclasePegmatitic
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103-281Camptonite: (Na-Fe amphibole lamprophyre)Phenocrysts of euhedral titanaugite in a groundmass of plagioclase(?) & acicular microlite of barkevikite; calcite & zeolites in amygdules; iron orePorphyritic with a microcrystalline groundmass, somewhat vesicular.Jakuben, Bohemia
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103-283Quartz porphyryQuartz (10-15%), plagioclase phenocrysts (20%), calcite (40%±), pyrite (5%±)Porphyritic with a microcrystalline groundmass. Highly calcitized.On Hwy 299 NE of Redding, 1 mile beyond Furnaceville, Calif.Cannot locate area-SFJ 9/71
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103-285Quartz dioriteQuartz (35%), plagioclase (40%), hornblende (20%), chlorite (5%), clinozoisite (5%)Holocrystalline, hypidiomorphic, medium-grainedOn road to Iron Mt., W of Redding, E edge of French Gulch Quad., Calif.Cannot locate area-SFJ 9/71
96
103-291Granodiorite porphyryQuartz, plagioclase, orthoclaseDike rock (based on field occurance)NE outlier of Hinkley Hills outlier, Sec. 28, T10N, R2W, Barstow Quad., Calif.
97
103-292Gabbro, PyroxenePlagioclase (40%, An50?), augite (50%, 2v=45, opt +, sligh Ti pleo?) being replaced? by hornblende (grn-brn pleo, 5-10%) and opaques (ilmenite?), olivine (partly altered to serpentine & ? chlorite,iddingsite?, less than 5%)Dark gray variety, poikilitic, allotiomorphic, granular, medium-grainedNE slope of Iron Mt., NE 1/4 Sec. 18 T9N, R2W, Barstow Quad., Calif.
98
103-293Gabbro, AlteredUralitized hornblende (55%), plagioclase (45%)Poikilitic, allotriomorphic; uralitizedNE slope of Iron Mt., NE 1/4 Sec. 18 T9N, R2W, Barstow Quad., Calif.Loc. OK--SFJ 3/70
99
103-294Aplite: Garnet, muscoviteQuartz, plagioclase, muscovite, garnetDikes in hornblende gabbroNE slope of Iron Mt., NE 1/4 Sec. 18 T9N, R2W, Barstow Quad., Calif.Loc. OK--SFJ 3/70
100
103-295FelsiteIn draw NE of road, 1.6 mi. W of Bakersfield turnoff from Hwy 58 north of Barstow on Hwy 266, near W edge of SE 1/4 Sec. 35, T10N, R2W, Barstow Quad., Calif.Loc. OK--SFJ 3/70