Chalcopyrite
Image: James Petts from London, England (CC BY-SA 2.0)
Mineral NameChalcopyrite
Chemical FormulaCuFeS2
Mohs Hardness3.5
Crystal Systemtetragonal
Lustermetallic
Streak Colorgreenish-black
Cleavagepoor/indistinct
Fractureuneven
Specific Gravity4.2
Colorsbrass-yellow, golden-yellow, iridescent tarnish
Transparencyopaque
Type LocalityWorldwide, e.g., Butte, Montana, USA; Rio Tinto, Spain
Mineral GroupSulfides
Usesmajor ore of copper, collector's specimens
Associated Mineralspyrite, sphalerite, galena, quartz, calcite
Raritycommon
Description
The image shows a close-up of brass-yellow, metallic chalcopyrite crystals and masses embedded within a lighter, possibly quartz or feldspar, matrix.
Geological Context
Chalcopyrite forms in various geological settings, including hydrothermal veins, disseminated in igneous and metamorphic rocks, and in massive sulfide deposits. It is the most important primary ore mineral for copper.
