mineral

Likely raw tourmaline (black schorl)

Schorl tourmaline, complex borosilicate mineral: NaFe²⁺₃Al₆(BO₃)₃Si₆O₁₈(OH)₄

AI-generated identification · may be incorrect

Black to brown-black, commonly vitreous to submetallic, with prismatic striated crystals and uneven fracture; Mohs hardness 7–7.5, specific gravity about 3.1–3.3. The photograph suggests a dark, partly crystalline specimen, though identification from one image is provisional.

Identified September 19, 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 geologically young to Precambrian depending on the deposit.

Uses & applications

Used as a mineral specimen and occasionally as a black gemstone; tourmaline’s piezoelectric and pyroelectric properties support scientific and specialty applications. Fine crystals have modest collector value.

Geological facts

Schorl is the most common tourmaline species and is strongly pleochroic in transparent crystals. Black tourmaline is often sold as a decorative or metaphysical stone.

Field identification & locations

Look for elongated, vertically striated prismatic crystals, black color, hardness sufficient to scratch glass, and possible electric charge when warmed or rubbed; common sources include Brazil, Afghanistan, Pakistan, Madagascar, and the United States.