mineral
Tourmaline
Schorl (Complex boron silicate, NaFe3Al6(Si6O18)(BO3)3(OH)4)
Hardness: 7 to 7.5 on the Mohs scale. Color: Typically black (schorl). Luster: Vitreous to resinous. Crystal structure: Trigonal, prismatic crystals often with striated faces. Cleavage: Indistinct. Specific gravity: 3.0 to 3.2
- Hardness
- 7 to 7
- Color
- Typically black (schorl)
- Luster
- Vitreous to resinous
Identified More mineral →
Explore Tourmaline in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 to 7.5 on the Mohs scale. Color: Typically black (schorl). Luster: Vitreous to resinous. Crystal structure: Trigonal, prismatic crystals often with striated faces. Cleavage: Indistinct. Specific gravity: 3.0 to 3.2
Formation & geological history
Forms in pegmatites, hydrothermal veins, and metamorphic rocks like schists and gneisses through the crystallization of boron-rich magmatic fluids.
Uses & applications
Used in gemstone and jewelry trade, industrial applications due to piezoelectric and pyroelectric properties, and as a popular mineral specimen for collectors.
Geological facts
Tourmaline has one of the widest color ranges of any mineral group, but black tourmaline (schorl) accounts for about 95% of all tourmaline found in nature.
Field identification & locations
Easily identified by its characteristic prismatic crystal habit with distinct vertical striations and triangular cross-sections. Found worldwide, with notable deposits in Brazil, Africa, the United States, and Madagascar.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Soil with Mineral Detritus and Quartz Fragments
Regolith / Silicate Mineral Aggregate
sedimentary
Limonite / Goethite (Iron Ore Mineral nodule)
FeO(OH)·nH2O / FeO(OH)
mineral
Schist
Schist
Metamorphic
Septarian Pebble
Septarian nodule / Concretion
sedimentary
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral