mineral

Black Tourmaline (Schorl)

Sodium Iron Aluminum Borosilicate (NaFe2+3Al6(Si6O18)(BO3)3(OH)3OH)

Hardness: 7-7.5 on Mohs scale; Color: Jet black; Luster: Vitreous to resinous (sub-metallic when polished); Crystal Structure: Hexagonal (Trigonal); Cleavage: Indistinct; Specific Gravity: 3.0-3.2

Hardness: 7-7
Color: Jet black
Luster: Vitreous to resinous (sub-metallic when polished)

Identified March 23, 2026More mineral →

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Physical properties

Hardness: 7-7.5 on Mohs scale; Color: Jet black; Luster: Vitreous to resinous (sub-metallic when polished); Crystal Structure: Hexagonal (Trigonal); Cleavage: Indistinct; Specific Gravity: 3.0-3.2

Formation & geological history

Formed in igneous and metamorphic rocks, most commonly in pegmatites through hydrothermal processes. Schorl can be found in formations ranging from 100 million to over 1 billion years old.

Uses & applications

Used primarily in jewelry as a gemstone, as specimens for metaphysical mineral collecting, and historically in industrial gauges due to its piezoelectric properties.

Geological facts

Black Tourmaline is pyroelectric, meaning it develops an electrical charge when heated. It is the most common variety of tourmaline, accounting for approximately 95% of all tourmaline found in nature.

Field identification & locations

Identify by its deep black color, high hardness (cannot be scratched by steel), and characteristic striations (parallel lines) along the crystal length if unpolished. Commonly found in Brazil, Namibia, and the United States (Maine/California).

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