Chalcopyrite is a sulfide mineral that crystallises in the tetragonal system. It has chemical composition CuFeS2, a golden yellow colour and hardness 3,5 to 4 on the Mohs scale.
Chalcopyrite is one of the most important copper ores. Due to its colour it is often confused with Pyrite though this mineral has a cubic and not a tetragonal crystal system. Chalcopyrit is also somewhat more yellowish in colour.