mineral

Black tourmaline (schorl) crystal fragments

Schorl, NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

AI-generated identification · may be incorrect

Typically black to dark brown with vitreous to resinous luster; Mohs hardness 7–7.5, trigonal crystal structure, and no prominent cleavage. The pictured pieces are irregular, fractured fragments with some prismatic faces.

Identified August 23, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly in boron-rich granitic pegmatites and hydrothermal veins as magma cools, commonly during the Paleozoic to Cenozoic eras. Common sources include Brazil, Afghanistan, Madagascar, Namibia, and the United States.

Uses & applications

Used as a collector mineral, ornamental stone, and occasionally in jewelry; fine crystals can be faceted, while broken fragments have limited commercial use.

Geological facts

Schorl is the most common tourmaline species and is strongly piezoelectric and pyroelectric, developing electrical charge when compressed or heated.

Field identification & locations

Identify it by its opaque black color, elongated striated crystals, high hardness, and often triangular or rounded-triangular cross-section; distinguish it from magnetite, which is more metallic and strongly magnetic. Common specimens are widely sold in pegmatite collections.