mineral

Schorl (Black Tourmaline) in Quartz Matrix

Schorl: NaFe3Al6(BO3)3Si6O18(OH)4 (Complex Borosilicate)

Hardness: 7-7.5 (Mohs scale); Color: Jet black (Schorl) with white/translucent (Quartz); Luster: Vitreous to resinous; Crystal structure: Trigonal (often long, columnar, or needle-like crystals with vertical striations); Cleavage: Indistinct; Specific Gravity: 3.0-3.2

Hardness: 7-7
Color: Jet black (Schorl) with white/translucent (Quartz)
Luster: Vitreous to resinous

Identified March 18, 2026More mineral →

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Physical properties

Formation & geological history

Formed in granitic pegmatites and metamorphic rocks through hydrothermal processes where boron and iron are present in the final stages of magma crystallization. These specimens can range from hundreds of millions to billions of years old.

Uses & applications

Schorl is widely used for industrial purposes due to its piezoelectric properties. It is also a very popular stone for metaphysical collecting, specimen display, and occasionally cabochon jewelry.

Geological facts

Black tourmaline (Schorl) is both pyroelectric and piezoelectric, meaning it can generate an electrical charge when heated, cooled, or under pressure. In the 1700s, Dutch traders used the crystals to pull ash out of their Meerschaum pipes.

Field identification & locations

Identify in the field by the long, columnar black crystals with rounded triangular cross-sections and heavy vertical striations embedded in white quartz or feldspar. Found globally in pegmatites like those in Brazil, Namibia, and the San Diego County mines.

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