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Metallic minerals as precipitants of silver and gold

1913; Volume: 8; Issue: 2 Linguagem: Inglês

10.2113/gsecongeo.8.2.140

1554-0774

Chase Palmer,

Metal Extraction and Bioleaching

of the U.S. Geological Survey but as the phenomena under discussion appear .tohave an important application in the study of ore deposits, particularly .insecondary enrichment, it has seemed best in this prelimin.ary paper to outline the fiel.do.f investigation and thus make the main results immediately available to economic geologists.The literature bearing directly or indirectly on the precipitation of the precious metals by sulphides is widely scattered and for this reason is summarized below.The earliest important work on this subject by W. Skey • published in •87• in a New Zealand publication appears to have wholly escaped the attention of economic geologists until very recently.Skey's work, however, blocked out one of the most interesting and promising fields of research in the province o.f ore deposits.LITERATURE.The earliest article of note which deals wi, th the precipitation of precious metals by metallic minerals was written by C. Wilkinson and appeared .in•867 .•'In .thisWilkinson reports certain experiments in which he obtained a deposit of gold on pyrite, galena, chalcopyrite, arsenopyrite, stibnite, molybdenite, sphalerite and wolframite when these were immersed, together with a piece o• wood or leather, in a solution of AuCla.When the experiments were repeated with most of these without organic matter being present, no precipitate was obtained.Wilkinson concludes that "organic matter is the necessary chemical agent to decompose a solution of the chloride of gold in order to precipitate the gold as a coherent coating around a nucleus presented to it."In •87o W. Skey, who was familiar with Wilkinson's results, repeated these experimen,ts.He took care to exclude all organic • W. Skey, "On the Reduction of Certain Metals from their Solutions by Metallic Sulphides, and the Relation of This to the Occurrence of Such Metals in the Native State," Trans.and Proc.New Zealand Institute, Vol.III., •87•.