4.2" Green Augelite Crystals on Quartz - Peru

Augelite (chemical formula Al2PO4(OH)3) is an aluminum phosphate mineral that occurs as a product of metamorphism in phosphate-bearing sedimentary rocks, in granitic pegmatites, and in veins of high-heat hydrothermal ore deposits. Crystals can be colorless or exhibit green, yellow, white, blue, pink and red coloration, depending on impurities present during formation. Due to augelite's relatively low hardness and brittle tenacity, it is seldom used for faceting into a gemstone.

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.