2.8" Quartz Crystals on Atacamite - Peru

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.

Atacamite is a secondary copper (halide) mineral formed from the oxidation of copper minerals--it has been found in the patina on the Statue of Liberty! It has the chemical formula Cu₂Cl(OH)₃ and forms as slender prismatic crystals, fibrous crystals and as granular to compact aggregations. It was first described by Russian mineralogist Dmitri de Gallitzin after specimens were found in the Atacama Desert of Chile in 1801.