Beautiful Proustite Crystals from Morocco Minerals 5:05 PM A+ A- Print Email Proustite | Formula: Ag₃AsS₃ System: Trigonal Colour: Scarlet, Vermilion or ... Lustre: Adamantine Hardness: 2 - 2½ From: Imiter Mine, Imiter, Djebel Saghro, Ouarzazate, Souss-Massa-Draâ, Morocco Photo Credit: Christian Rewitzer