3.7" Pyrite With Galena and Calcite Crystals - Peru
This is beautiful specimen of gleaming, pyritohedral formed pyrite crystals, surrounded by galena and calcite. It comes from the Huanzala Mine in Peru and the entire piece measures 3.7" across.
The mineral pyrite or iron pyrite is commonly referred to as Fool's Gold because it's 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. Smaller (druzy) crystal aggregates may give off a beautiful glistening effects, and larger crystals may be perfectly formed, including fascinating cubes, penetration twins, and other interesting crystal forms.
Galena is a lead based mineral that is in fact the primary ore of lead, and has been used for its lead content for thousands of years. Galena typically displays a gray metallic luster and forms cubes or octahedral crystals. The chemical composition of galena is PbS.
Calcite, CaCO3, is a carbonate mineral and the most stable polymorph of calcium carbonate. The other polymorphs are the minerals aragonite and vaterite. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals. However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, and prisms. Calcite exhibits several twinning types adding to the variety of observed forms. It may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form. Its fracture is conchoidal, but difficult to obtain.