mineral

Schorl (Black Tourmaline)

Schorl (Sodium Iron Aluminum Borosilicate Hydroxide), NaFe3Al6(BO3)3Si6O18(OH)4

Hardness: 7-7.5 (Mohs scale); Color: Inky black; Luster: Vitreous to sub-metallic; Crystal Structure: Trigonal/Hexagonal (often prismatic with vertical striations); Cleavage: Indistinct; Specific Gravity: 3.0-3.2

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

Identified May 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in pegmatites through hydrothermal processes and late-stage magmatic crystallization. It is also found in some metamorphic rocks like schists. Typically ranges from Precambrian to recent geological periods.

Uses & applications

Used widely for spiritual/metaphysical purposes (protection stone), geological specimen collecting, and occasionally as a source of boron in industrial applications.

Geological facts

Black tourmaline is pyroelectric and piezoelectric, meaning it can generate an electrical charge when heated or subjected to mechanical stress. It is the most common variety of the tourmaline group, making up 95% of all tourmaline found in nature.

Field identification & locations

Identify in the field by its deep black color, lack of transparency, and especially the deep vertical striations on the long faces of the crystal. It often has a rounded triangular cross-section.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

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

metamorphic

Gypsum (variety Selenite or Alabaster)

Calcium sulfate dihydrate (CaSO4·2H2O)

Mineral

Nephrite Jade

Nephrite

Mineral/Rock

Granite

Granite (Phaneritic intrusive igneous rock)

igneous