Digenite is a scarce copper sulfide mineral, Cu9S5. It has a metallic luster, dark bluish-gray to blackish color, dark gray streak, and a Mohs hardness of 2.5 to 3. Itís usually massive, but can form pseudocubic crystals. Broken surfaces show conchoidal fracture. Primary digenite occurs in some copper-bearing hydrothermal veins, some intrusive igneous rocks, and in some sulfide exhalative deposits.
Digenite-rich hydrothermal vein sample (2.25 cm across along the base) from the Leonard Mine at Butte, southwestern Montana, USA. In this area, digenite occurs in 62 to 66 million year old copper sulfide-rich hydrothermal veins that intrude the Butte Quartz Monzonite, a pluton of the Boulder Batholith (mid-Campanian Stage, late Late Cretaceous, 76 million years).