2.7" Galena, Sphalerite and Quartz Association - Peru
This is a beautiful association of galena, sphalerite and quartz crystals that formed from a dolomite and quartz matrix. It comes from the Huanzala Mine in Peru and the entire specimen measures 2.7" long.
Silicon Dioxide, also know as SiO2 or Quartz, is the second most abundant mineral in the Earth's crust. Quartz crystals generally grow in silica-rich, hot watery solutions called hydrothermal environments, at temperatures between 100°C and 450°C, and usually under very high pressure. Quartz veins are formed when open fissures are filled with hot water during the closing stages of mountains forming, and can be hundreds of millions of years old.
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.
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.