Cu 2 FeS 4 Composition Copper iron sulfide Color Copper to yellowish brown on fresh surface. Quickly tarnishes purple, blue, and red. Octahedral crystals are extremely rare.
Bornite occurs mostly massive , as well as in groups of tiny crystals.
Purple Copper Ore. Additional false names describing Bornite are also known. Striking Features Tarnish, low hardness, and association with copper ores . Commonly Occurs With Pyrite , Calcite , Barite , Galena , Chalcopyrite , Chalcocite, Magnetite Noteworthy Localities Bornite is common and found in many locations. The province of Cornwall, England has produced many specimens, including some crystallized examples. Large, distinct crystals come from Dzhekazgan Oblast, Kazakhstan.