Green Tourmaline

Green tourmaline is a natural mineral: the green color range of tourmaline, a group of closely related borosilicate mineral species. Its trade name verdelite is described by Mindat as a green variety of tourmaline, most commonly elbaite or fluor-elbaite, with various other species possible. IGS reserves verdelite for green stones not colored by chromium or vanadium; intense green stones colored by those elements are sold as chrome tourmaline.

Products made with this material

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Tourmaline (dark green)
Tourmaline (dark green)

10mm

$9.99 Available

Full material guide
Material facts

What the material is, where it comes from or how it is made, identification and care, from the cited sources.

Properties

Nature Natural mineral (green color variety of tourmaline)
Mineral species Tourmaline group; most commonly elbaite or fluor-elbaite
Chemical formula Elbaite: Na(Li1.5,Al1.5)Al6Si6O18(BO3)3(OH)4
Color Light to dark green
Cause of color Traces of iron, and possibly titanium; chrome tourmaline is colored by chromium or vanadium
Crystal system Trigonal
Refractive index 1.624 to 1.644 (tourmaline, GIA)
Birefringence 0.018 to 0.040
Specific gravity 3.06 (+0.20, −0.06)
Mohs hardness 7 to 7.5
Electrical property Pyroelectric and piezoelectric: becomes electrically charged when heated or squeezed

Origins & sources

Most gem tourmalines are elbaites, which form in granite-containing pegmatites. Tourmaline is most commonly found in Brazil, where most production over the centuries has come from pegmatites in Minas Gerais, and it is also mined in Afghanistan, Pakistan, Kenya, Madagascar and Mozambique. IGS lists green elbaite from Nuristan, Afghanistan, and Kashmir, India; Mindat records verdelite from many localities, including Minas Gerais, Brazil, and Varuträsk, Sweden.

Identification

Dark green tourmaline shows particularly strong pleochroism: a stone can look forest green face-up but olive green from the sides, and the color along the crystal length is deeper. IGS classes green tourmaline as usually eye-clean. Heating to lighten blue and green stones is common, stable and undetectable. IGS calls names such as "Brazilian emerald" or "Ceylonese peridot" for green tourmaline unacceptable, because emerald and peridot are different gem species.

Care

GIA rates tourmaline 7 to 7.5 on the Mohs scale with fair toughness. It is generally stable to light and is not affected by chemicals, but high heat can change its color and sudden temperature changes can make it fracture. Colors produced by irradiation can fade with heat or bright light. Clean it with warm, soapy water; ultrasonic and steam cleaners are not recommended.

History & culture

History

In the 1500s a Spanish conquistador in Brazil confused green tourmaline crystals with emerald; GIA dates the first recorded green tourmaline crystal, the "Brazilian emerald", to Francisco Spinoza's expedition in 1554. The confusion lasted until scientists recognized tourmaline as a distinct mineral species in the 1800s. Mindat derives verdelite from the Latin viridis, "green", and the Greek lithos, "stone".

Cultural meanings

According to GIA, ancient mystics believed tourmaline could inspire artistic expression because of its wide range of colors. GIA also reports the belief that green tourmaline promotes courage, strength and stamina.

Traditional beliefs

Tourmaline is listed as a birthstone for October, alongside opal, and as the gem of the eighth wedding anniversary.

Sources

Collected Oct 23, 2026