mineral
Black Tourmaline (Schorl)
NaFe3+3Al6(BO3)3Si6O18(OH)4
Hardness: 7-7.5 on Mohs scale. Color: Opaque jet black. Luster: Vitreous to resinous, high polish. Crystal structure: Trigonal/hexagonal. Cleavage: Indistinct. Specific gravity: 3.0-3.2.
- Hardness
- 7-7
- Color
- Opaque jet black
- Luster
- Vitreous to resinous, high polish
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Physical properties
Hardness: 7-7.5 on Mohs scale. Color: Opaque jet black. Luster: Vitreous to resinous, high polish. Crystal structure: Trigonal/hexagonal. Cleavage: Indistinct. Specific gravity: 3.0-3.2.
Formation & geological history
Formed in igneous environments, primarily within granitic pegmatites, hydrothermal veins, and metamorphic rocks rich in boron.
Uses & applications
Widely used for gemstone jewelry, lapidary cabochons, palm stones, and in crystal healing practices as a protective stone.
Geological facts
Black Tourmaline is pyroelectric and piezoelectric, meaning it can generate an electrical charge when heated, cooled, or subjected to mechanical pressure.
Field identification & locations
Identified by its deep jet-black color, high hardness, glassy polished surface, and occasional small surface fractures or lighter mineral inclusions. Commonly found in Brazil, Madagascar, Africa, and the USA.
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