mineral

Tourmaline (Mixed colors)

Boron silicate mineral (Na,Ca)(Li,Mg,Al,Fe,Mn,Ti,V,Cr)3Al6(BO3)3Si6O18(OH,F)4

Mohs hardness: 7 to 7.5; Color: Virtually every color (pink, green, blue, black, yellow); Luster: Vitreous; Crystal structure: Trigonal; Cleavage: Indistinct; Specific Gravity: 3.06

Hardness: 7 to 7
Color: Virtually every color (pink, green, blue, black, yellow)
Luster: Vitreous

Identified June 26, 2026More mineral →

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Physical properties

Mohs hardness: 7 to 7.5; Color: Virtually every color (pink, green, blue, black, yellow); Luster: Vitreous; Crystal structure: Trigonal; Cleavage: Indistinct; Specific Gravity: 3.06

Formation & geological history

Commonly forms in granitic pegmatites and metamorphic rocks like schist and marble. It crystallizes from hydrothermal fluids during the late stages of magmatic cooling.

Uses & applications

Widely used as a gemstone in jewelry, especially when transparent. It is also used in pressure gauges due to its piezoelectric properties and in scientific instruments.

Geological facts

Tourmaline is both pyroelectric and piezoelectric, meaning it can generate an electrical charge when heated or compressed. It was once used by Dutch traders to pull ash out of their tobacco pipes.

Field identification & locations

Identify in the field by its characteristic rounded triangular cross-section and vertical striations along the prism faces. Found globally, with major deposits in Brazil, Madagascar, and Afghanistan.

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

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral