mineral

Rough Green Tourmaline (Verdelite)

Elbaite (Complex Silicate) - Na(Li,Al)3Al6(BO3)3Si6O18(OH)4

Hardness: 7-7.5 on Mohs scale; Color: Dark olive green to forest green; Luster: Vitreous to sub-vitreous; Crystal Structure: Trigonal (hexagonal prisms); Cleavage: Indistinct; Specific Gravity: 3.0-3.26.

Hardness: 7-7
Color: Dark olive green to forest green
Luster: Vitreous to sub-vitreous

Identified March 23, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in granitic pegmatites or metamorphic rocks like schist and marble through hydrothermal activity. They typically form during the final stages of magma crystallization where rare elements become concentrated.

Uses & applications

Used widely in jewelry as a gemstone. Industrially, it is used in pressure gauges due to its piezoelectric and pyroelectric properties (it generates an electric charge when heated or squeezed).

Geological facts

Green tourmalines are known as Verdelite. Because of its complex chemical composition, it has been called a 'mineral garbage can.' Dutch traders once used heated tourmaline crystals to pull ash out of their meerschaum pipes, calling them 'aschentrekkers'.

Field identification & locations

Identify in the field by its characteristic vertical striations (parallel lines) along the length of the crystal and a rounded triangular cross-section. Common locations include Brazil, Afghanistan, Africa, and Maine/California in the USA.

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