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jordanite

n. (context mineralogy English) A grey monoclinic sulfosalt mineral with chemical formula Pb14(As,Sb)6S23.

Wikipedia
Jordanite

Jordanite is a sulfosalt mineral with chemical formula Pb(As,Sb)S in the monoclinic crystal system, named after the German scientist Dr H. Jordan (1808–1887) who discovered it in 1864.

Lead-grey in colour (frequently displaying an iridescent tarnish), its streak is black and its lustre is metallic. Jordanite has a hardness of 3 on Mohs scale, has a density of approximately 6.4, and a conchoidal fracture.

The type locality is the Lengenbach Quarry in the Binn Valley, Wallis, Switzerland.