3.4" Black Tourmaline (Schorl), Goethite & Orthoclase - Namibia
This is an association of orthoclase feldspar, black tourmaline (schorl) and a brown formation of goethite after siderite, collected from the Erongo Mountains in Namibia. Under short wave UV light, the feldspar fluoresces a vibrant pink-red color.
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.
Orthoclase is a feldspar mineral with the chemical formula KAlSi₃O₈ and has a hardness of 6 - 6.5 on the Mohs hardness scale. It is considered a key component in many igneous rock formations and is one of the more abundant minerals throughout the continental crust. It can form individual crystals, however it's most commonly known for its pink coloration within granite rock. It has many commercial uses, including application in the production of a wide variety of ceramics and is sometimes used in the manufacturing of glass.