Chalcopyrite. Image source: Mineralogical Information Institute.
Chalcopyrite, also called copper pyrites, is the most important copper ore (CuFeS2), very similar to pyrite, with which it is often associated in sulfide veins in igneous and certain metamorphic rocks. The crystals are tetragonal but often occur in masses. Hardness: 3.5–4; relative density 4.2. Clacopyrite is found in the United States, Canada, Australia, western Europe, and South America.