mineral

Black Tourmaline (Schorl)

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

Hardness: 7-7.5. Color: Inky black. Luster: Vitreous to sub-metallic. Crystal structure: Trigonal/Hexagonal. Cleavage: Indistinct. Specific Gravity: 3.0 to 3.2. Form: Characteristically shows vertical striations.

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

Identified July 8, 2026More mineral →

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Physical properties

Formation & geological history

Formed in granitic pegmatites, hydrothermal veins, and metamorphic rocks such as schists. This sodium iron borosilicate mineral crystallizes from hot fluids rich in boron.

Uses & applications

Used primarily as a gemstone, in spiritual practices as a protection stone, and industrially in pressure gauges due to its piezoelectric and pyroelectric properties.

Geological facts

Schorl is the most common member of the tourmaline group, making up 95% of all tourmaline found in nature. It was used by early Dutch traders to pull ash out of their tobacco pipes because it becomes electrically charged when heated.

Field identification & locations

Identified by its deep black color, vertical striations (parallel grooves) on the faces, and a non-distinctive cleavage. Frequently found in Brazil, Namibia, and the USA (California and Maine).

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