mineral

Black Tourmaline

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

Hardness: 7-7.5 on Mohs scale; Color: Black; Luster: Vitreous to sub-metallic; Crystal structure: Trigonal/Hexagonal with vertical striations (furrows); Cleavage: Indistinct; Specific Gravity: 3.0-3.2

Hardness: 7-7
Color: Black
Luster: Vitreous to sub-metallic

Identified April 4, 2026More mineral →

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Physical properties

Formation & geological history

Forms in igneous and metamorphic rocks, most notably in granitic pegmatites and hydrothermal veins. It develops as mineral-rich hot fluids cool and crystallize over millions of years.

Uses & applications

Commonly used in 'healing' and metaphysical practices as a grounding stone. Industrially, its piezoelectric properties make it useful for pressure gauges and some electrical components. Also used as a gemstone when high-quality crystals are found.

Geological facts

Black Tourmaline (Schorl) is the most common variety of tourmaline, accounting for approximately 95% of all tourmaline found in nature. It is pyroelectric, meaning it can generate an electrical charge when heated.

Field identification & locations

Identify in the field by its distinct deep vertical striations (parallel grooves) along the length of the crystal and its characteristic triangular or rounded-triangular cross-section. Commonly found in Brazil, Africa, and the USA (Maine and California).