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Gold/Mining/Energy : Desert Dirts, Gold & Platinum, the emperors new clothes -- Ignore unavailable to you. Want to Upgrade?

To: go4it who wrote (1449)	6/4/1998 9:52:00 AM
From: Aurum	Read Replies (2) \| Respond to of 1913

Charles, iridium does interfere in the standard fire assay (and probably in all fire assays except where the "finish" is by some specific method of analysis such as AAS (atomic absorption spectrophotometry). However, the interference is a positive one - that is, the assay value obtained for the gold will be higher than the real value. This is because the prill of precious metal obtained after the cupellation stage of the standard fire assay will contain any platinum group metals that were in the sample. This is sometimes not quite true because the fire assay sometimes does not collect all of the platinum group elements. However, this point does not alter the fact that iridium (or any other PGE) will not prevent the gold in the sample from being collected. Theoretically (and I have never heard of it happening, and it is just too improbable) if the gold in the sample was alloyed with a lot of iridium (and perhaps one or two other PGEs) it would not be effectively collected in the SFA. However, I have never heard of a natural gold-iridium alloy, and there are good practical and theoretical reasons for believing that it would not occur in significant amounts in nature. In the above I note that I did not make it clear that the interference occurs because in a SFA the prill of precious metal is weighed. Hence any contained PGEs get weighed as gold (ie. a positive interference). I hope this is of some use to you, Regards - Aurum