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Cu2S
Monoclinic
Chalcocite, a copper sulfide mineral, was first reported from Franklin by Palache (1935) and has subsequently been found in additional assemblages at both Franklin and Sterling Hill. Although a significant local host for Cu, it is a minor mineral here and has no economic significance locally.
Chalcocite is dark gray-black, commonly oxidized (sooty) on exposure, and sectile. It is sometimes confused with djurleite, from which it is best differentiated using X-ray methods. Secondary malachite, azurite, and brochantite are common alteration products. There are no chemical analyses of local material.
Chalcocite from Franklin occurs in seams in the ore, commonly associated with magnetite or franklinite; quartz is common to some assemblages. The most noteworthy occurrence is as the matrix for fine magnetite crystals and native silver, described under magnetite.
Chalcocite is known from several assemblages at Sterling Hill, in particular with rhodonite on the 700 level and with franklinite and calcite from the north orebody. An occurrence below the 700 level was noted by Jenkins and Misiur (1994). Small amounts are found in the common sulfide veins, in atypical assemblages not noted here, and in many one-of-a-kind specimens.
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| Copyright © 1995 by Pete J. Dunn |
Website
by Herb Yeates
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Link
to homepage
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This
page created: January 11, 2001 |
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