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.

Quartz is the name given to silicon dioxide (SiO2) and is the second most abundant mineral in the Earth's crust. Quartz crystals generally grow in silica-rich environments--usually igneous rocks or hydrothermal environments like geothermal waters--at temperatures between 100°C and 450°C, and usually under very high pressure. In either case, crystals will precipitate as temperatures cool, just as ice gradually forms when water freezes. Quartz veins are formed when open fissures are filled with hot water during the closing stages of mountain formation: these veins 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.
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DETAILS
SPECIES
Gypsum var. Selenite & Quartz Chalcedony
LOCATION
Lily Mine, Pisco Umay, Ica Department, Peru
SIZE
2.4" wide
CATEGORY
ITEM
#98175