mineral

Black Tourmaline

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

Hardness: 7-7.5 on Mohs scale; Color: Black, sometimes with brownish tint; Luster: Vitreous to resinous; Crystal structure: Trigonal/Hexagonal columns with vertical striations; Specific gravity: 3.0-3.25

Hardness: 7-7
Color: Black, sometimes with brownish tint
Luster: Vitreous to resinous

Identified June 5, 2026More mineral →

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Physical properties

Formation & geological history

Primarily forms in igneous pegmatites and metamorphic rocks like schist and marble through hydrothermal processes. Most specimens date from hundreds of millions of years old.

Uses & applications

Used in minor industrial pressure gauges due to piezoelectric properties; extensively used in jewelry, metaphysical collections, and as a protective stone specimen.

Geological facts

Black Tourmaline is pyroelectric, meaning it can generate an electrical charge when heated. It was historically used by Dutch traders to pull ash out of their meerschaum pipes, earning the name 'Aschentrekker' (ash puller).

Field identification & locations

Look for deep vertical striations (grooves) along the length of the crystal and a triangular cross-section. Found globally in Brazil, Madagascar, Namibia, and the USA (California/Maine).