Chalcopyrite ore mineral of copper; crystallises in the tetragonal crystal system, but crystals are generally small with diphenoidal faces resembling the tetrahedron; usually massive with a metallic lustre and brass or golden-yellow colour; shows greenish-black streaks, uneven fracture and indistinct cleavage; hardness is 3.5-4 on Moh's scale and specific gravity is 4.1-4.3. Chalcopyrite is also known as copper pyrite or yellow pyrite and because of its physical appearance it is also called 'fools' gold'. It occurs in mesothermal or hypothermic deposits. The upper part of the Rajmahal Traps has been highly weathered and there is indication of the presence of chalcopyrite and chalcocite in the rocks. However, chalcopyrite is not very stable as it has low hardness as compared to other heavy minerals and as such it is extremely rare in heavy mineral suites of various vertical sections of the Chittagong, Chittagong Hill Tracts and surma basin of Bangladesh and assam and tripura states of India.