mineral

Black Tourmaline (Schorl)

Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)

Hardness: 7-7.5 on Mohs scale; Color: Black to brownish-black; Luster: Vitreous to sub-vitreous; Crystal Structure: Trigonal (often hexagonal prisms in raw form); Cleavage: Indistinct; Specific Gravity: 3.0-3.2

Hardness: 7-7
Color: Black to brownish-black
Luster: Vitreous to sub-vitreous

Identified July 14, 2026More mineral →

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Physical properties

Formation & geological history

Forms in igneous and metamorphic rocks, most notably in granitic pegmatites, hydrothermal veins, and schists. It is a complex silicate mineral containing boron.

Uses & applications

Primarily used for gemstone collecting, lapidary work, and spiritual/metaphysical jewelry. Some high-quality specimens are used in scientific instruments for their piezoelectric properties.

Geological facts

Black tourmaline is both pyroelectric (generates electricity when heated) and piezoelectric (generates electricity under pressure). 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 vertical striations along the length of the crystal, triangular cross-section, and intense black color. Found worldwide, with major deposits in Brazil, Namibia, and the USA (California and Maine).

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Sandstone with Mineral Veining or Crust

Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)

sedimentary

Schist

Metamorphic

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

mineral

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic