1.9" Chalcopyrite and Cubic Pyrite Association - Peru
This is beautiful cluster of gleaming, brassy chalcopyrite with pyrite crystals. There is a small amount of sphalerite within a cavity on this specimen. It comes from the Huanzala Mine in Peru and the entire specimen measures 1.9" wide.
The mineral pyrite or iron pyrite is commonly referred to as Fool's Gold because its metallic luster and pale brass-yellow hue give it a superficial resemblance to gold. In the old mining days, pyrite was sometimes mistaken for gold. Pyrite is the most common of the sulfide minerals with the chemical formula FeS2. Pyrite crystals occur in many shapes and habits, including cubes of all sizes, penetration twin cubes, pyritohedral clusters and as small druzy crystals that can exhibit a beautiful glistening effect.
Chalcopyrite is a brass-yellow colored mineral which is one of the most important ores of copper. When weathered chalcopyrite loses it's metallic luster, turning a gray-green color. When acids are present the tarnish can develop a red to blue to purple iridescence.
Sphalerite is a part of the sulfides group and typically exhibits a grey/black appearance due to high concentrations of impurities. When sphalerite is in it's purest state, the chemical composition is ZnS, and can display a gemmy transparent light tan/yellow color. This is one of the few minerals that can form crystals ranging anywhere between gemmy and transparent to opaque and metallic-like. Opaque or cloudy sphalerite tends to be most abundant, due to the ease of iron replacing zinc in the process of formation.