mineral
Tourmaline crystal
Tourmaline Group (Complex Borosilicate)
Hardness of 7-7.5 on Mohs scale, typically prismatic crystals with vertical striations, vitreous to subresinous luster, specific gravity 3.0-3.2, no true cleavage.
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Physical properties
Hardness of 7-7.5 on Mohs scale, typically prismatic crystals with vertical striations, vitreous to subresinous luster, specific gravity 3.0-3.2, no true cleavage.
Formation & geological history
Forms in pegmatites and hydrothermal veins associated with granitic magmas, as well as in metamorphic rocks like schists and marbles.
Uses & applications
Used as gemstones in jewelry, in pressure-sensing equipment due to piezoelectric properties, and highly sought after by mineral collectors.
Geological facts
Tourmaline displays a wide variety of colors and can exhibit pleochroism, where the color changes depending on the viewing angle.
Field identification & locations
Easily identified by its characteristic triangular cross-section and distinct parallel striations along the length of the crystal prism.
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