3.4" Metallic, Needle-Like Pyrolusite Cystals in Quartz - Morocco

Pyrolusite is a mineral consisting of manganese dioxide (MnO2) and is important as an ore of manganese. It has a silvery metallic luster, a black or bluish-black streak, and readily soils the fingers. It commonly is found in finely packed fibrous, acicular, and radial forms composed of very fine needles or fibers.

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.