Common and important copper ore mineral, Cu5FeS4; sp. gr. 5.0–5.1; hardness 3; cubic; reddish-brown to various shades of purplish-blue, the colours iridescent on tarnished surfaces; pale grey streak; metallic lustre; crystals rough cubes, rhombododecahedra, can also be massive; cleavage poor {111}; occurs in hydrothermal veins, in zones of secondary enrichment, and in various syngenetic copper ores, porphyry copper deposits, skarns, etc.; soluble in nitric acid.