mineral
Black Tourmaline
Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)
AI-generated identification · may be incorrectHardness: 7-7.5; Color: Inky black; Luster: Vitreous to sub-metallic; Crystal structure: Trigonal/Hexagonal; Cleavage: Indistinct; Specific Gravity: 3.0-3.2.
- Hardness
- 7-7
- Color
- Inky black
- Luster
- Vitreous to sub-metallic
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Physical properties
Hardness: 7-7.5; Color: Inky black; Luster: Vitreous to sub-metallic; Crystal structure: Trigonal/Hexagonal; Cleavage: Indistinct; Specific Gravity: 3.0-3.2.
Formation & geological history
Formed in igneous and metamorphic rocks, specifically in granitic pegmatites and schists; rich in iron, often dating back hundreds of millions of years.
Uses & applications
Used in jewelry, as an abrasive, in pressure gauges due to piezoelectric properties, and highly valued by mineral collectors for protection symbolism.
Geological facts
Tourmaline is both pyroelectric and piezoelectric, meaning it can generate an electrical charge when heated or squeezed. It was historically used by Dutch traders to pull ash from long-stemmed pipes.
Field identification & locations
Identify by its deep black color, vertical striations (furrows) along the crystal length, and triangular cross-sections. Commonly found in Brazil, Namibia, and the United States (Maine/California).
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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
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
Septarian Pebble
Septarian nodule / Concretion
sedimentary