1.6" Black Tourmaline (Schorl) Crystals on Orthoclase - Namibia

Schorl, also known as "black tourmaline" or "black schorl", is a black form of tourmaline that often occurs as lustrous prismatic crystals. The crystals can be stubby or elongated and typically feature lengthwise striations. Many schorl crystals have flattened pyramidal terminations. They can also form in radiating, columnar, and stalactitic aggregations, as well as small, needle-like inclusions within quartz (tourmalinated quartz) and in massive form.

Schorl is a basic sodium iron aluminum boro-silicate with the generic chemical formula NaFe2 + 3Al6(BO3)3Si6O18(OH)4 . It has been used for everything from jewelry to piezoelectric guitar pickups.

Orthoclase is a feldspar mineral with the chemical formula KAlSi₃O₈ and 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 most abundant minerals throughout the continental crust. It can form individual crystals, but it is 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.