Home > Silver Minerals – October 23 > MS0665 Xanthoconite with Proustite

Xanthoconite with Proustite


Xanthoconite and proustite are polymorphs of silver arsenic sulfide. Both species have same chemical composition, but where proustite has hexagonal symmetry, xanthoconite has monoclinic symmetry. Unlike other well known "ruby silver" minerals, xanthoconite is distinctly yellow. In fact, the name means "yellow powder" in Greek (Breithaupt, 1840). Engel & Nowacki (1968) solved the crystal structure of the mineral. This Chilean specimen likely dates to the late nineteenth century, and bears an attached vintage paper label. Incomplete, red proustite crystals to 5 mm lay on matrix, showing contacting from the other side of the seam. A honey yellow xanthoconite crystal group, 0.8 mm across, sit safely in a depression on the front surface. From the Arthur Flagg (1882–1961) collection.

Price: $150

Item code: MS0665

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