2.4" Red-Brown Jarosite & Quartz Association - Colorado Mine, Utah

This is a small cluster of reddish-brown jarosite crystals that formed in association with quartz crystals. This mineral association was collected from the Colorado Mine in the Tintic District of Utah. There is some iridescence along one edge of the specimen and the quartz is covered in a layer of what is likely iron oxidation.

Jarosite is the most common mineral of the alunite supergroup with a base chemical formula of KFe3+ 3(SO4)2(OH)6. The crystals are usually found as brown to amber-yellow granular crusts or coatings within cavities. The crystals are often very small: larger crystal formations are considered relatively rare. The crystals are most often found with tabular and/or pseudo-cubic structures.

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.

Jarosite & Quartz
Colorado Mine, Tintic District, Utah
2.4 x 2"