mineral

Schorl (Black Tourmaline) in Quartz and Feldspar

NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH)

Hardness: 7 on Mohs scale; Color: Jet black (schorl), white to grayish (quartz/feldspar); Luster: Vitreous to sub-metallic; Crystal structure: Trigonal; Cleavage: Indistinct; Specific gravity: 3.0-3.2

Hardness: 7 on Mohs scale
Color: Jet black (schorl), white to grayish (quartz/feldspar)
Luster: Vitreous to sub-metallic

Identified April 8, 2026More mineral →

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Physical properties

Formation & geological history

Formed in granitic pegmatites during the final stages of cooling from silicate magmas rich in boron. These specimens can range from hundreds of millions to billions of years old.

Uses & applications

Used primarily for mineral specimens, ornamental carvings, and in metaphysical practices. Some industrial use in manufacturing pressure gauges due to piezoelectric properties.

Geological facts

Black tourmaline is a 'borosilicate' mineral. It is pyroelectric, meaning it can generate an electrical charge when heated, and piezoelectric, generating a charge under mechanical stress.

Field identification & locations

Identify by its characteristic prismatic crystals with vertical striations (furrows) along the faces. Commonly found in Brazil, Namibia, and some parts of the USA like Maine and California.

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