mineral
Black tourmaline (schorl)
Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
AI-generated identification · may be incorrectBlack to dark brown, vitreous-to-submetallic luster; Mohs hardness 7–7.5; trigonal crystal system with lengthwise striations and imperfect cleavage. The specimen appears rough and irregular, so identification from the image is not certain.
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Physical properties
Black to dark brown, vitreous-to-submetallic luster; Mohs hardness 7–7.5; trigonal crystal system with lengthwise striations and imperfect cleavage. The specimen appears rough and irregular, so identification from the image is not certain.
Formation & geological history
Forms in boron-rich granitic pegmatites and metamorphic rocks as magma cools; tourmaline-group minerals occur in rocks spanning a wide range of geological ages.
Uses & applications
Used as a collectible mineral and, when clear and well-formed, as a gemstone; industrial use is limited.
Geological facts
Schorl is the most common tourmaline species and often occurs as long, striated prismatic crystals.
Field identification & locations
Look for black color, strong lengthwise grooves, and a hard, glassy surface; common in pegmatites worldwide, including Brazil, Afghanistan, and the United States.
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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
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Granite
Granite (Phaneritic intrusive igneous rock)
igneous