mineral

Black tourmaline

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

AI-generated identification · may be incorrect

Typically black, opaque, and vitreous to resinous, with strong longitudinal striations and prismatic crystals; Mohs hardness 7–7.5, no prominent cleavage, specific gravity about 3.1–3.3. The fragment appears consistent with a dark, striated prismatic mineral, though a photo alone cannot confirm identity.

Identified September 16, 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; specimens range from Precambrian to recent geological settings. Common localities include Brazil, Afghanistan, Pakistan, Madagascar, Namibia, and the United States.

Uses & applications

Used as a collectible mineral, ornamental stone, and occasional gemstone; fine crystals are popular in metaphysical markets. It has limited industrial use compared with other tourmaline varieties.

Geological facts

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

Field identification & locations

Look for a black, glassy prismatic form with parallel grooves, uneven fracture, and attraction to charged dust after rubbing; distinguish it from coal, obsidian, and hornblende by its crystal striations and hardness. Identification should be confirmed by hardness, streak, and mineral testing.