5.4" Tangerine Quartz Crystal Cluster - Madagascar

These clusters are natural and not heat treated or unnaturally coated. The orange color is caused by a combination of iron, hematite, and manganese coating the surface of the crystals, but may also be present as inclusions within the crystals themselves. A likely cause is a high iron content in the soil where these crystals are found.

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.