mineral
Tumbled Black Tourmaline
Schorl (NaFe2+3Al6Si6O18(BO3)3(OH)3OH)
AI-generated identification · may be incorrectHardness: 7-7.5 (Mohs scale), Color: Black, Luster: Vitreous to resinous, Crystal structure: Trigonal, Cleavage: Indistinct, Specific gravity: 3.1-3.2
- Hardness
- 7-7
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Physical properties
Hardness: 7-7.5 (Mohs scale), Color: Black, Luster: Vitreous to resinous, Crystal structure: Trigonal, Cleavage: Indistinct, Specific gravity: 3.1-3.2
Formation & geological history
Typically forms in pegmatites, granites, and metamorphic rocks. Age varies widely depending on the host rock. Often found in association with quartz and feldspar.
Uses & applications
Commonly used as a gemstone, particularly in tumbled form for jewelry or metaphysical purposes. Also collected as mineral specimens. Historically used for mourning jewelry.
Geological facts
Black tourmaline is the most common variety of tourmaline, accounting for about 95% of all tourmaline in nature. It is strongly pyroelectric and piezoelectric.
Field identification & locations
Identified by its distinctive black color, hardness, and often striated prismatic crystals (though lost in tumbled stones). Commonly found in Brazil, Africa, and parts of the USA.
