Chalcopyrite
Chalcopyrite is an ore of copper with by products of gold and silver. In fact, 80 %
of worlds copper comes from this ore.
It usually forms brittle,
metallic, compact masses with a brassy yellow, often
tarnished or iridescent color, but is also found as
striated tetragonal crystals. It's streak is greenish black
and commonly occurs in igneous rocks as the original
constituent from which many other copper minerals have
been derived by alteration. It also occurs in pegmatites,
contact metamorphic zones in limestone, and sulfide ore
veins. It sometimes contains gold and silver as impurities.