mineral
Tourmalinated Quartz or Schorl
Silicate mineral, specifically Schorl (NaFe2+3Al6(Si6O18)(BO3)3(OH)4) or dark Tourmaline crystal cluster
Mohs hardness of 7 to 7.5; color is typically pitch black with a vitreous to resinous luster; crystal system is trigonal, often showing striated columnar prismatic crystals; specific gravity is approximately 3.0 to 3.2.
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Physical properties
Mohs hardness of 7 to 7.5; color is typically pitch black with a vitreous to resinous luster; crystal system is trigonal, often showing striated columnar prismatic crystals; specific gravity is approximately 3.0 to 3.2.
Formation & geological history
Forms in pegmatites and hydrothermal veins associated with granitic magmas, often crystallizing during the late stages of magma cooling under high pressure and temperature.
Uses & applications
Used in mineral collecting, lapidary arts, metaphysical practices, and occasionally in industrial applications due to its piezoelectric and pyroelectric properties.
Geological facts
Tourmaline has one of the widest ranges of colors of any mineral group, but black tourmaline, known as schorl, is the most common variety, accounting for about 95% of all tourmaline in nature.
Field identification & locations
Easily identified by its characteristic striated triangular or prismatic crystal cross-sections and high hardness. Found worldwide, with notable deposits in Brazil, Africa, and the USA.
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