2.4" Green Quartz Chalcedony & Selenite Association - Peru

This is a fascinating formation of quartz chalcedony with selenite, that was collected from the Lily Mine in Peru. The chalcedony formed in a copper-rich environment, which explains the blue-green color.

Silicon Dioxide, also known 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.

Selenite is a variety of gypsum, a soft sulfate mineral that is composed of calcium sulfate dihydrate (CaSO4 · H2O). When chemically pure, gypsum is transparent and colorless, however, impurities give the gypsum a diverse range of colors and formations. Desert rose, selenite and satin spar are just a few of the varieties of gypsum known to have formed though hydrothermal processes.
Gypsum var. Selenite & Quartz Chalcedony
Lily Mine, Pisco Umay, Ica Department, Peru
2.4" wide