mineral

Raw black tourmaline (schorl)

Schorl, NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

AI-generated identification · may be incorrect

Black, opaque, and typically vitreous to submetallic with strong prismatic crystal habit and uneven fracture; Mohs hardness 7–7.5, no distinct cleavage, and specific gravity about 3.1–3.3. The image appears to show a rough, fractured piece with reflective crystal faces.

Identified August 21, 2026More mineral →

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Physical properties

Formation & geological history

Forms mainly in boron-rich granitic pegmatites and hydrothermal veins during late-stage magma crystallization, commonly in Paleozoic to younger continental crust. Associated minerals include quartz, feldspar, and mica.

Uses & applications

Used as a collector mineral, ornamental stone, and occasionally in jewelry; tourmaline’s piezoelectric and pyroelectric properties support scientific and specialty technical uses. Common rough pieces have modest commercial value.

Geological facts

Schorl is the most abundant tourmaline species and commonly occurs as elongated, striated prisms. Heating or pressure can produce electrical charges at its ends.

Field identification & locations

Identify it by its jet-black color, lengthwise striations, glassy luster, hardness, and tendency to form three-sided or six-sided prisms; common localities include Brazil, Afghanistan, Madagascar, Pakistan, and the United States. A photo alone cannot exclude black minerals such as biotite or hornblende.