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Geostats Pty Ltd - Certified Reference Material Product Catalogue Listing
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This listing details the statistics and other information relative to Certified Reference Materials (CRMs) available from Geostats Pty Ltd.
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10/4/2006
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For an up-to-date copy of this listing, please visit our website:www.geostats.com.auVersion:1/4/2013
http://www.geostats.com.au/Standards%20List%20-%20Website.xls
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All materials have a grain size smaller than 75 micron with a nominal mean around 45 micron and all have been tested extensively using a number of reputable laboratories worldwide. These methods of manufacture and testing produce reliable working statistics on homogeneous materials.
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All materials detailed in these lists are available in good supply, and at competitive prices. Worldwide door-to-door delivery is available, and purchase orders are generally processed and delivered within 15 working days of ordering.
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Gold and Base Metal reference materials are generally packaged in sealed plastic containers with screw lids. Relevant control statistics are printed on the side of the container. Gold CRMs are sold in 1 kilogram lots, while base metal CRMs are sold in 250 gram lots. All CRMs can be packaged in weights ready for submission to the laboratories. Heat-sealed plastic sachets are used for this purpose. There is a charge per packet applicable to this service.
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Sulphur and Carbon CRMs are sold individually in 10 gram air tight plastic or aluminium packets. This minimises the chance of contamination and oxidation of the contents.
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The following description details the potential usage of these materials in the mineral exploration industry.
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Measuring the Accuracy of Analyses
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Certified reference materials are used to measure the accuracy of reported analyses. These should be representative of at least three grades relevant to the materials being tested, one low, one mid-range and one high.
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All of the CRMs should be similar in colour and two different materials are recommended for each of the three grades. An example would be CRMs grading 0.70, 0.85, 2.80, 3.10, 7.50 and 8.20. The laboratory must not be able to recognize materials from colour or first pass analyses.
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These materials should be included with both normal coarse samples and with pulped repeat samples. Results of analyses on these materials should determine whether accompanying assay data is entered into the project database.
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QC Filter prior to entry into database
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Data should not be transferred directly from e-reports or laboratory hard copies to the project database. It is essential to instigate a quality checking process prior to database entry. This involves confirming that certified reference materials are reported within their tolerance limits. This would generally mean plus or minus 3 standard deviations.
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It is important that anomalous results are discussed with the laboratory as soon as possible after reporting.
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A database built using good quality control protocols can be presented to the board or bank as a VALIDATED database.
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This makes decisions easier for everyone concerned.
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Usage
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These materials are for use in the mining industry as reference materials for monitoring and testing the accuracy of laboratory assaying. Shipments of this material are classified as pulverised underground rock samples for importation and customs purposes.
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Preparation
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All materials are dried in an oven for a minimum of 12 hours at 110oC. The dry material is then pulverised to better than 75 micron (nominal mean of 45 micron) using an Air Classifier. The material is then homogenised and stored in a sealed, stable container ready for final packaging.
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Materials are statistically sampled from stores, then packaged into either heat sealed, air tight, plastic pulp packets or screw top sealed plastic containers ready for distribution. All packaging has been chosen to ensure minimal contamination from outside sources during shipment, use and storage.
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Assay Testwork
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All materials are tested thoroughly in the Geostats semi-annual laboratory survey. This involves assaying by a minimum of 50 reputable laboratories selected from across the world. Results are compiled into a comprehensive report detailing statistics for each material. Assay distributions are checked and processed statistically, producing monitoring statistics for these CRMs. Materials are tested regularly to ensure stability and homogeneity.
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Details about the statistics provided
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Average
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The average grade for the material is determined using the analyses performed during the certification process. This is the target grade for the material.
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Standard Deviation
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The standard deviation for the grade of the material is also calculated using the analyses from the certification process. This indicates the likely spread of the analyses performed on the material. It is expected that the laboratory can return results within 3 times the standard deviation of the target grade.
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Count
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The count is the number of analyses used to certify the material.
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95% CI
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The 95% confidence limit refers to the margin of error in the mean expected at 95% confidence. I.e. we can be 95% confident that the true mean lies between average minus error and average plus error. The confidence interval is an indication of the quality of testwork on the material and the quality of the material itself, not to be confused with the control limits for assaying.
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