Little Black Blobs in the Background

I am sure that many of us remember “mineralogy” from our student days as beginning with the orthosilicate group, passing quickly through sorosilicates to beryl, then through pyroxenes and amphiboles, and on to micas, feldspars, and the silica minerals. Amphiboles were studied to exhaustion, their nomenclature (now mostly discarded) being then regarded as of prime importance. Sulfides, on the other hand, were almost completely ignored, despite their economic importance and significance, as we now know, as agents of climate cooling. In petrography classes, sulfides were classified together with oxides as “opaques” and dismissed from further consideration.

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