Crystal of proustite — Photo: Parent Géry · Public domain
Proustite
Also known as: Light ruby silver.
Silver sulfarsenide — 'ruby silver' — a striking scarlet mineral and an important silver ore.
Intro adapted from Wikipedia (CC BY-SA).
Proustite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Ag₃AsS₃.
It crystallizes in the hexagonal crystal system (space group R3c).
Key properties: Mohs hardness 2–2.5; specific gravity 5.57; typically red; Vermilion streak; Adamantine luster; optically uniaxial.
IMA symbol Prs, grandfathered status — known before the IMA’s founding, named in 1832.
A late-forming mineral in hydrothermal deposits, in the oxidized and enriched zone, in association with other silver minerals and sulfides.
It is found associated with Silver, arsenic, xanthoconite, stephanite, acanthite, tetrahedrite, chlorargyrite.
The mineral was named to honor Joseph Louis Proust (1754–1826), celebrated French chemist.
Collections: Collector Favorites, Rare & Remarkable.