Home > Silver Minerals – October 23 > MS1005 Xanthoconite with Proustite

Xanthoconite with Proustite - Sold

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 material come out of Imiter in 2007-2008 when many proustite specimens came onto the mineral market. There are two crystals of xanthoconite to 1 mm present, and larger red crystals of proustite to 2 mm. Excellent microphotography potential. Please note that this piece has two saw cuts.