mineral
Black tourmaline (schorl)
Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
AI-generated identification · may be incorrectBlack, opaque, vitreous to resinous luster; Mohs hardness 7–7.5; trigonal crystals, commonly striated lengthwise, with indistinct cleavage. The pictured fragment lacks clear crystal form, so identification is provisional.
Identified More mineral →
Explore Black tourmaline (schorl) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Black, opaque, vitreous to resinous luster; Mohs hardness 7–7.5; trigonal crystals, commonly striated lengthwise, with indistinct cleavage. The pictured fragment lacks clear crystal form, so identification is provisional.
Formation & geological history
Forms in boron-rich granitic pegmatites and some metamorphic rocks as magma cools and fluids crystallize; deposits range from ancient to geologically recent.
Uses & applications
Used as a gemstone, mineral specimen, and occasionally as an ornamental stone; tourmaline is also valued for its electrical and pyroelectric properties.
Geological facts
Schorl is the most common tourmaline species and is typically black due to iron content.
Field identification & locations
Look for a very hard, dark crystal with lengthwise grooves and a roughly triangular cross-section; common sources include Brazil, Afghanistan, Pakistan, and the United States. A small rough fragment like this typically sells for about $2–$15, depending on quality and locality.
More like this
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