Several classic European localities have produced highly desirable Proustite specimens. Relatively large crystals have come from the Erzgebirge in Germany at Freiberg, Schlema, and the Schneeberg Districts. Across the border in the Czech Republic, some of the earliest sources Proustite have come from Jáchymov, Krušné Hory Mts, Bohemia. Small Proustite crystals, often associated with Quartz
, were once found in the Ste Marie-aux-Mines, Haut-Rhin, Alsace, France.
A more recent producer of good Proustite crystals is Morocco, at the Imiter and Bou Azzer mines. In South America, some of the best examples of this mineral have come from Chañarcillo, Copiapo Province, Chile; and the Uchucchacua Mine, Oyon, Lima Department, Peru. In Canada, good crystal clusters and crusts of Proustites have come from the Cobalt region, Timiskaming District, Ontario.