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Assay Information

BLM Runs Test on Assayers

Recommended reading before you get your samples tested!

The Bureau of Land Management (BLM) conducted a multi-year study of sixty-five assay laboratories, completed in late 2002, to determine the accuracy of their testing procedures. The laboratories, all located in North America, were provided with ore samples of known concentrations without benefit of identifying the source as BLM. Payment was rendered for the service provided.

Most laboratories involved were sent 4 samples containing known values of gold, silver, platinum, and palladium, and 2 samples that were complex blanks. Prices charged for assay services varied from $60 for fire assays to $2,250 for a “tin fusion method.” In our review of the report, price did not seem to be reflected as a determining factor for accuracy. In some cases, a lower cost for the service provided a more accurate assay.

The results of assays conducted are compiled in a 34-page report, including 16 pages detailing the reasons for and methods used in the study and 18 pages of results. The volume of the report did not allow for inclusion in the Journal, but we have made the entire document available free through the links below. You can check and see how a particular individual or company did in the tests before you submit your samples.

Many of the results published were well within acceptable limits, but some were so far out in “left field” that utilization could be disastrous—attempting to open a mine based on poor assays is the same as throwing your money away. Substantial quantities of precious metals were reported in some blanks. Some samples that contained valuable quantities of precious metals were reported as “none detected.” As a result of this report, several assay labs were barred from advertising in our publication.

BLM should be applauded for conducting this badly needed study, and hopefully they will continue this public service. The resulting report should be a valuable tool as a validation for assay services.

Study preface (.pdf file) 0.8MB

Study results (.pdf file) 1.0MB

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