mineral

Raw black tourmaline

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

AI-generated identification · may be incorrect

Typically black, vitreous to submetallic, opaque, with Mohs hardness 7–7.5; commonly forms trigonal prismatic crystals with strong lengthwise striations and indistinct cleavage. The specimen appears massive or fractured rather than a well-formed crystal.

Identified August 30, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly in granite pegmatites and hydrothermal veins during late-stage igneous crystallization; most specimens are geologically hundreds of millions to billions of years old. Common localities include Brazil, Afghanistan, Pakistan, Madagascar, Namibia, and the United States.

Uses & applications

Used as a gemstone, ornamental material, metaphysical specimen, and in limited technical applications involving piezoelectric and pyroelectric properties; black schorl is generally more valuable for collecting than jewelry.

Geological facts

Tourmaline can develop electric charges when heated or compressed, a property called pyroelectricity or piezoelectricity. Black schorl is the most abundant tourmaline variety.

Field identification & locations

Identify it by its black color, glassy luster, strong longitudinal striations, relatively high hardness, and lack of reaction to dilute acid; a streak test is usually brownish-black. A firm identification may require testing specific gravity or crystal form.