mineral

Black Tourmaline (Schorl)

Schorl (NaFe2+3Al6(Si6O18)(BO3)3(OH)3OH)

AI-generated identification · may be incorrect

Hardness: 7-7.5 (Mohs), Color: Deep black, Luster: Vitreous to sub-metallic, Crystal Structure: Trigonal (striated prisms), Cleavage: Indistinct, Specific Gravity: 3.0-3.2

Hardness: 7-7

Identified July 20, 2026More mineral →

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Physical properties

Hardness: 7-7.5 (Mohs), Color: Deep black, Luster: Vitreous to sub-metallic, Crystal Structure: Trigonal (striated prisms), Cleavage: Indistinct, Specific Gravity: 3.0-3.2

Formation & geological history

Typically forms in granitic pegmatites, hydrothermal veins, and metamorphic rocks such as mica schists. It is rich in boron and iron, forming during the late stages of magma crystallization.

Uses & applications

Commonly used in metaphysical practices for protection and grounding, as an ore for boron, in scientific instruments due to its piezoelectric properties, and as jewelry for collectors.

Geological facts

Tourmaline is both pyroelectric (develops charge when heated) and piezoelectric (develops charge under pressure). In the 1700s, Dutch traders used it to pull ash from their pipes, calling it 'aschentrekker'.

Field identification & locations

Identified in the field by its characteristic long, needle-like or prismatic crystals with vertical striations and its distinct triangular or rounded-triangular cross-section. Commonly found in Brazil, Namibia, and the USA.