mineral
Black Tourmaline
Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)
AI-generated identification · may be incorrectHardness 7.0-7.5, black opaque color, vitreous to sub-metallic luster, trigonal crystal system with vertical striations, no true cleavage, specific gravity 3.0-3.3
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Physical properties
Hardness 7.0-7.5, black opaque color, vitreous to sub-metallic luster, trigonal crystal system with vertical striations, no true cleavage, specific gravity 3.0-3.3
Formation & geological history
Found in granitic pegmatites, metamorphic rocks, and hydrothermal veins. Formed from boron-rich fluids during final stages of magma crystallization.
Uses & applications
Used in gemstone and jewelry trade, industrial pressure gauges (due to piezoelectricity), filtering, and as a popular protection stone for collectors.
Geological facts
It is pyroelectric, meaning it generates an electric charge when heated. It also features a unique triangular cross-section in its raw crystal form.
Field identification & locations
Identify by its intense black color, deep vertical striations on sides, and lack of cleavage. Common in Brazil, Namibia, and USA (California/Maine).
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Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous