mineral
Black tourmaline (schorl)
Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
AI-generated identification · may be incorrectTypically black with a vitreous-to-submetallic luster and lengthwise striations; Mohs hardness 7–7.5, trigonal crystal structure, poor cleavage, and specific gravity about 3.0–3.3. The rough, elongated crystal form is consistent with schorl, though the image alone cannot confirm identification.
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Physical properties
Typically black with a vitreous-to-submetallic luster and lengthwise striations; Mohs hardness 7–7.5, trigonal crystal structure, poor cleavage, and specific gravity about 3.0–3.3. The rough, elongated crystal form is consistent with schorl, though the image alone cannot confirm identification.
Formation & geological history
Forms in boron-rich granitic pegmatites and some metamorphic rocks as magma cools and fluids crystallize; pegmatites commonly formed during the Precambrian to recent geologic history.
Uses & applications
Collected as a mineral specimen and occasionally used in jewelry; tourmaline’s piezoelectric properties have niche technical applications.
Geological facts
Schorl is the most common tourmaline species and can occur in large, striated crystals.
Field identification & locations
Look for black, elongated, strongly striated crystals with uneven or conchoidal fracture, often associated with quartz and feldspar in pegmatites. Found 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
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