mineral
Black Tourmaline (Schorl)
Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)
Hardness: 7-7.5 on Mohs scale; Color: Jet black; Luster: Vitreous to sub-metallic; Crystal structure: Trigonal; Cleavage: Indistinct; Specific gravity: 3.0-3.2.
- Hardness
- 7-7
- Color
- Jet black
- Luster
- Vitreous to sub-metallic
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Physical properties
Hardness: 7-7.5 on Mohs scale; Color: Jet black; Luster: Vitreous to sub-metallic; Crystal structure: Trigonal; Cleavage: Indistinct; Specific gravity: 3.0-3.2.
Formation & geological history
Formed in igneous and metamorphic rocks, most commonly in pegmatites through hydrothermal processes during final stages of magma crystallization.
Uses & applications
Used as a gemstone, in industrial pressure gauges (due to piezoelectricity), and popular in jewelry and metaphysical collecting.
Geological facts
Schorl is the most common member of the tourmaline group, making up 95% of all tourmaline found in nature. It is pyroelectric, meaning it can generate an electrical charge when heated.
Field identification & locations
Identified by its deep black color, vertical striations on crystal faces, and triangular or hexagonal cross-sections. Commonly found in Brazil, Namibia, and the USA (California/Maine).
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Mineral
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