mineral

Schorl (Black Tourmaline)

NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH)

AI-generated identification · may be incorrect

Hardness: 7-7.5 (Mohs scale), Color: Jet black to brownish-black, Luster: Vitreous to resinous, Crystal Structure: Trigonal, Cleavage: Indistinct, Specific Gravity: 3.0-3.2

Hardness: 7-7

Identified July 13, 2026More mineral →

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Physical properties

Hardness: 7-7.5 (Mohs scale), Color: Jet black to brownish-black, Luster: Vitreous to resinous, Crystal Structure: Trigonal, Cleavage: Indistinct, Specific Gravity: 3.0-3.2

Formation & geological history

Commonly formed in igneous pegmatites and metamorphic rocks like schists and marbles. It occurs through hydrothermal activity where boron-rich fluids crystallize. Its age can range from hundreds of millions to billions of years depending on the host formation.

Uses & applications

Mainly used as a decorative specimen for mineral collectors. Industrially, it has been used in pressure gauges due to its piezoelectric properties, though it is most popular today in metaphysical jewelry and home decor.

Geological facts

Black tourmaline is piezoelectric (develops an electric charge when under pressure) and pyroelectric (develops a charge when heated). It is the most common variety of the tourmaline group, making up 95% of all tourmaline in nature.

Field identification & locations

Identify in the field by its characteristic vertically striated (grooved) triangular crystal faces and jet-black color. It is common worldwide, with major deposits in Brazil, Namibia, and the United States (Maine and California).