But in both minerals, the substitution is minor and no solid solution is believed to exist between the two minerals. Proustite is the rarer of the two minerals and is usually found in the same ore veins with pyrargyrite, silver and other silver sulfides. Fine crystals, with their transparency, luster and color, are very attractive mineral specimens. However, as with other silver minerals, it is reactive to light and can form a white coating upon exposure. This coating can be wiped off, but fine specimens should be stored in closed containers with exposure to light limited.
Color is a bright scarlet red to reddish orange.
Luster is adamantine. Crystals are translucent to transparent. There is no perpendicular mirror plane and therefore a hemimorphic crystal can be seen, in some rare examples, with differing terminations at the top and bottom of the crystal. Also found massive. Cleavage is sometimes distinct in three directions forming rhombohedrons.