chalcopyrite (copper pyrites) Most common copper mineral, CuFeS₂; sp. gr. 4.1–4.3; hardness 3.5–4.0; tetragonal; brass-yellow, often with an iridescent tarnish; greenish-black streak; metallic lustre; sometimes massive, crystals usually tetrahedra; cleavage imperfect pyrrhotine; primary mineral found in igneous rocks and hydrothermal veins, in association with pyrite, pyrrhotine, cassiterite, sphalerite, galena, calcite, and quartz, an important mineral in porphyry copper deposits, and also occurs in quartz diorite, and in pegmatites, crystalline schists, porphyry copper deposits, syngenetic copper ores and skarns, and contact metamorphic zones. It is deeper in colour than pyrite, more brittle and harder than gold, is soluble in nitric acid, and its alteration products are secondary copper minerals. It is a major ore mineral for copper.

chalcopyrite (copper pyrites) Opaque, brass-coloured, copper iron sulphide (CuFeS₂); the most important copper ore. It is found in sulphide veins and in igneous and contact metamorphic rocks. The crystals are tetragonal but often occur in masses. Hardness 3.5–4; r.d. 4.2.