mineral

Green Tourmaline

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

Hardness: 7-7.5 (Mohs scale), Color: Emerald green to bottle green, Luster: Vitreous, Crystal structure: Trigonal/Hexagonal (prismatic), Cleavage: Indistinct, Specific Gravity: 3.06

Hardness: 7-7

Identified June 12, 2026More mineral →

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Physical properties

Hardness: 7-7.5 (Mohs scale), Color: Emerald green to bottle green, Luster: Vitreous, Crystal structure: Trigonal/Hexagonal (prismatic), Cleavage: Indistinct, Specific Gravity: 3.06

Formation & geological history

Formed in granitic pegmatites and metamorphic rocks like schists. The location (Ratnapura district, Sri Lanka) is famous for alluvial deposits where primary gems have weathered out into secondary gravels.

Uses & applications

Primarily used as a gemstone in high-end jewelry and as a collector's mineral specimen. Some lower-grade industrial tourmaline is used for its piezoelectric properties.

Geological facts

Sri Lanka is known as the 'Gem Island' (Ratna-Dweepa); many green tourmalines from this region were historically mistaken for emeralds. It is distinctive for its pleochroism, appearing different colors from different angles.

Field identification & locations

Identify by its characteristic prismatic crystal shape with vertical striations and high hardness. In Sri Lanka, they are often found in 'illam' (gem-bearing gravel layers).

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic