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As
Hexagonal
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| Figure 20-1. Crystal drawing of arsenic from Sterling Hill. Drawing is from Palache (1941b) who provided crystallographic data. | ||
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Arsenic was first reported from Sterling Hill by Palache (1941b) and has not been reported from Franklin. The known arsenic specimens consist of rare 0.5 to 5 mm crystals and blebs of dark gray, massive material up to 2 cm.
Palache measured and illustrated a flattened rhombohedral crystal and indentified the forms present (Figure 20-1). Arsenic is easily oxidized, and the known specimens have a black crust which is a mixture of arsenic and arsenolite, as identified employing XRD techniques. It is not known, however, if the arsenolite formed naturally before chemical dissolution of the host calcite in a laboratory process or formed contemporaneously with calcite-dissolution, or subsequently. Arsenolite, therefore, is not listed as a species from these deposits. Studied Sterling Hill arsenic is Sb-free and twinned on a microscopic scale.
Arsenic was found on the 900 level at Sterling Hill, where it occurs in a calcite matrix, associated with realgar, arsenopyrite, graphite, pyrite, zinkenite, and other minerals. A similar assemblage was found subsequently on the 1100 level, as mentioned under realgar, but arsenic has not as yet been indentified from this material.
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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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