mineral

Black Tourmaline (Schorl)

Schorl (Sodium iron silicate hydroxide boron silicate); NaFe3Al6(BO3)3Si6O18(OH)4

Hardness: 7-7.5 (Mohs scale); Color: Black (opaque); Luster: Vitreous to sub-metallic; Crystal structure: Trigonal/Hexagonal with vertical striations (parallel grooves); Cleavage: Indistinct; Specific gravity: 3.0-3.2

Hardness: 7-7
Color: Black (opaque)
Luster: Vitreous to sub-metallic

Identified March 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous and metamorphic rocks, most commonly in pegmatites through hydrothermal processes. Ages vary significantly based on the host rock formation, ranging from Precambrian to more recent geological eras.

Uses & applications

Predominantly used for metaphysical collecting, jewelry (beads/cabochons), and as a pressure sensor in certain industrial electronics due to its piezoelectric properties.

Geological facts

Black tourmaline is pyroelectric, meaning it can generate an electrical charge when heated. Throughout history, it was used by Dutch traders to pull ash out of their meerschaum pipes, leading to its nickname 'Aschentrekker' (ash puller).

Field identification & locations

Identify in the field by its characteristic elongated prismatic crystals with vertical striations and its triangular or rounded cross-section. Found globally in Brazil, Madagascar, Pakistan, and the USA (California/Maine). Beginners should look for its brittle, charcoal-like appearance that does not scratch glass.

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