mineral

Black Tourmaline (Schorl)

Schorl (Sodium Iron Aluminum Borosilicate Hydroxide), NaFe2+3Al6Si6O18(BO3)3(OH)3OH

Hardness: 7-7.5 (Mohs scale); Color: Jet black; Luster: Vitreous to sub-metallic; Crystal structure: Trigonal/Hexagonal with vertical striations; Cleavage: Indistinct; Specific gravity: 3.0 to 3.25.

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

Identified March 14, 2026More mineral →

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Physical properties

Hardness: 7-7.5 (Mohs scale); Color: Jet black; Luster: Vitreous to sub-metallic; Crystal structure: Trigonal/Hexagonal with vertical striations; Cleavage: Indistinct; Specific gravity: 3.0 to 3.25.

Formation & geological history

Formed primarily in pegmatites through hydrothermal processes where boron-rich fluids interact with granite. It is found in igneous and metamorphic environments dating from various geological eras, including Precambrian to Cenozoic.

Uses & applications

Used widely in metaphysical jewelry, as a protective talisman, and as a source of boron. Historically used in scientific instruments due to its pyroelectric and piezoelectric properties.

Geological facts

Black tourmaline is both pyroelectric (generates electricity when heated) and piezoelectric (generates electricity under pressure). It was famously used by Dutch traders to pull ash out of their Meerschaum pipes, leading to the name 'Aschentrekker' (ash puller).

Field identification & locations

Identify in the field by the long, columnar crystals with deep vertical grooves (striations) and a triangular or rounded triangular cross-section. Commonly found in Brazil, Namibia, and the United States (California/Maine).

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