mineral

Black Tourmaline

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: 3.0-3.2.

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

Identified January 22, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in igneous and metamorphic rocks, specifically in granitic pegmatites and schists; rich in iron, often dating back hundreds of millions of years.

Uses & applications

Used in jewelry, as an abrasive, in pressure gauges due to piezoelectric properties, and highly valued by mineral collectors for protection symbolism.

Geological facts

Tourmaline is both pyroelectric and piezoelectric, meaning it can generate an electrical charge when heated or squeezed. It was historically used by Dutch traders to pull ash from long-stemmed pipes.

Field identification & locations

Identify by its deep black color, vertical striations (furrows) along the crystal length, and triangular cross-sections. Commonly found in Brazil, Namibia, and the United States (Maine/California).

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