mineral

Black Tourmaline

Schorl (Sodium iron aluminum borosilicate), NaFe3Al6(BO3)3Si6O18(OH)4

Hardness: 7-7.5 on Mohs scale; Color: Jet black; Luster: Vitreous to sub-metallic; Crystal structure: Trigonal/Hexagonal with deep vertical striations; Cleavage: Indistinct; Specific Gravity: 3.0-3.2

Hardness: 7-7
Color: Jet black
Luster: Vitreous to sub-metallic

Identified May 10, 2026More mineral →

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Physical properties

Hardness: 7-7.5 on Mohs scale; Color: Jet black; Luster: Vitreous to sub-metallic; Crystal structure: Trigonal/Hexagonal with deep vertical striations; Cleavage: Indistinct; Specific Gravity: 3.0-3.2

Formation & geological history

Formed in igneous and metamorphic rocks, most commonly occurring in granitic pegmatites. It forms from boron-rich hydrothermal fluids during the final stages of magma crystallization.

Uses & applications

Primarily used for metaphysical or spiritual collections and as a semi-precious gemstone. Industrially used in pressure gauges due to its piezoelectric and pyroelectric properties.

Geological facts

Tourmaline is both pyroelectric (develops electric charge when heated) and piezoelectric (develops charge under pressure). In the 1700s, Dutch traders used the crystals to pull ash out of their tobacco pipes, calling it 'aschentrekker'.

Field identification & locations

Identify in the field by its black color, intense vertical striations on elongated prismatic crystals, and characteristic 'rounded triangle' cross-section. Commonly found in Brazil, Namibia, Madagascar, and the USA (California and Maine).

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