mineral

Possible black tourmaline (schorl) crystal

Schorl, NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

AI-generated identification · may be incorrect

Hardness 7–7.5 Mohs; opaque black to dark brown, vitreous-to-resinous luster, trigonal crystal structure, and commonly strong longitudinal striations. The specimen appears elongated and prismatic, though its heavily weathered or fractured surface limits certainty.

Identified August 23, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly in granitic pegmatites and hydrothermal veins as magma cools and boron-rich fluids crystallize; most specimens are Paleozoic to younger, depending on locality. Common sources include Brazil, Afghanistan, Pakistan, Madagascar, Namibia, and the United States.

Uses & applications

Used as a gemstone, ornamental mineral, metaphysical specimen, and occasionally in tourmaline electrical/thermal research; not generally used as aggregate or building stone.

Geological facts

Schorl is the most common tourmaline species and is frequently found with quartz, feldspar, and mica. Its prismatic striations and three-sided or six-sided cross-section are diagnostic.

Field identification & locations

Check for a glassy black surface, parallel grooves, hardness near quartz, and possible pyroelectric behavior when heated; distinguish it from coal or wood by its hardness and crystalline striations. Exact identification may require a loupe or testing.