mineral

Green Tourmaline (Verdelite)

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

Hardness: 7-7.5 (Mohs), Color: Dark forest green to olive, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: Indistinct, Specific Gravity: 3.0-3.3

Hardness: 7-7

Identified June 22, 2026More mineral →

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Physical properties

Hardness: 7-7.5 (Mohs), Color: Dark forest green to olive, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: Indistinct, Specific Gravity: 3.0-3.3

Formation & geological history

Formed in granitic pegmatites and metamorphic rocks through hydrothermal processes involving boron-rich fluids. Highly concentrated in regions with ancient tectonic activity.

Uses & applications

Primarily used as a gemstone in high-end jewelry and as a sought-after mineral specimen for collectors. In industry, it is sometimes used for its piezoelectric properties.

Geological facts

Tourmaline is unique because it becomes electrically charged when heated or squeezed (pyroelectricity/piezoelectricity). It often exhibits 'pleochroism,' meaning it displays different colors or shades when viewed from different angles.

Field identification & locations

Identify by its deep green color and characteristic vertical striations along the length of the crystal. Commonly found in Brazil, Namibia, Afghanistan, and Maine (USA). In the field, look for needle-like or columnar crystals embedded in quartz or feldspar.

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