mineral

Black Tourmaline

Schorl (NaFe2+3Al6(BO3)3Si6O18(OH)4)

Hardness 7 to 7.5 on Mohs scale. Opaque black color with a vitreous to resinous luster. Trigonal crystal system, often displaying prominent vertical striations along prismatic faces. Indistinct cleavage, subconchoidal to uneven fracture. Specific gravity around 3.0-3.3.

Identified July 23, 2026More mineral →

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Physical properties

Formation & geological history

Forms primarily in igneous rocks such as granites and granitic pegmatites, as well as high-grade metamorphic rocks like schists and gneisses via hydrothermal activity rich in boron.

Uses & applications

Popular in mineral collections, metaphysical practices, and occasionally used as a gemstone for beads or pendants. Industrially used historically in pressure gauges due to its pyroelectric and piezoelectric properties.

Geological facts

Black tourmaline (Schorl) is the most common variety of tourmaline, accounting for about 95% of all tourmaline found in nature. It exhibits pyroelectricity, meaning it develops an electric charge when heated.

Field identification & locations

Identified in the field by its deep black color, high hardness, parallel vertical striations on elongated crystal columns, and rounded triangular cross-section. Commonly found in Brazil, Madagascar, Pakistan, Namibia, and the USA (California, Maine).

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Sandstone with Mineral Veining or Crust

Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)

sedimentary

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

mineral

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Nephrite Jade

Nephrite

Mineral/Rock