mineral
Black Tourmaline
Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)
Hardness: 7-7.5 (Mohs scale), Color: Inky black, Luster: Vitreous to sub-metallic, Crystal Structure: Trigonal/Hexagonal columns with vertical striations, Cleavage: Indistinct/Poor, Specific Gravity: 3.0-3.2
- Hardness
- 7-7
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Physical properties
Hardness: 7-7.5 (Mohs scale), Color: Inky black, Luster: Vitreous to sub-metallic, Crystal Structure: Trigonal/Hexagonal columns with vertical striations, Cleavage: Indistinct/Poor, Specific Gravity: 3.0-3.2
Formation & geological history
Commonly formed in granitic pegmatites, hydrothermal veins, and metamorphic rocks such as schists. It is a complex borosilicate mineral formed through igneous and metamorphic processes over millions of years.
Uses & applications
Used primarily in jewelry as a gemstone, as a source of boron in industry, and widely collected as a metaphysical healing crystal or decorative mineral specimen. Historically used for scientific experiments due to its pyroelectric properties.
Geological facts
Black Tourmaline is pyroelectric and piezoelectric, meaning it generates an electrical charge when heated or subjected to pressure. Victorian grieving jewelry often used black tourmaline as a substitute for jet.
Field identification & locations
Identify in the field by its characteristic long, needle-like or columnar crystals with vertical grooves (striations) and a triangular cross-section. Commonly found in Brazil, Africa, and the USA (California and Maine).
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sedimentary
Schist
Schist
Metamorphic
Epidote
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metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Granite
Granite (Phaneritic intrusive igneous rock)
igneous