4.48" Schorl, Feldspar, and Quartz, Erongo Mountains, Namibia

This is a beautiful matrix of schorl (black tourmaline), feldspar, and quartz from the Erongo Mountains in Namibia. Although there are some minor abrasions, the specimen is in overall great shape, and there is a lot to explore.

Tourmaline is a crystalline boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Schorl, or black tourmaline, is the most common form of tourmaline, and has been used for everything from jewelry to piezoelectric guitar pickups.

Silicon Dioxide, also know as SiO2 or Quartz, is the second most abundant mineral in the Earth's crust. Quartz crystals generally grow in silica-rich, hot watery solutions called hydrothermal environments, at temperatures between 100°C and 450°C, and usually under very high pressure. Quartz veins are formed when open fissures are filled with hot water during the closing stages of mountains forming, and can be hundreds of millions of years old.

Feldspars are a group of rock-forming tectosilicate minerals. It is also one of the most common minerals on earth, making up nearly 60% of the crust.