mineral
Black Tourmaline (Schorl)
Sodium Iron Aluminum Borosilicate (NaFe2+3Al6(BO3)3Si6O18(OH)4)
AI-generated identification · may be incorrectHardness 7-7.5 on Mohs scale; color deep black to dark greenish-black; vitreous to resinous luster; trigonal crystal system with prominent vertical striations; perfect to poor cleavage, subconchoidal fracture.
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Physical properties
Hardness 7-7.5 on Mohs scale; color deep black to dark greenish-black; vitreous to resinous luster; trigonal crystal system with prominent vertical striations; perfect to poor cleavage, subconchoidal fracture.
Formation & geological history
Forms in granite pegmatites, hydrothermal veins, and metamorphic rocks under high-temperature and high-pressure geological conditions.
Uses & applications
Used widely in mineral collecting, ornamental carvings, lapidary arts, metaphysical/crystal healing practices, and historically in scientific instruments like pressure gauges due to its piezoelectric qualities.
Geological facts
Black tourmaline exhibits both pyroelectric and piezoelectric properties, meaning it can generate an electrical charge when heated or subjected to mechanical pressure.
Field identification & locations
Identified by its intense black color, high hardness, non-metallic shiny luster, and distinct parallel striations along elongated prismatic crystals. Commonly found in pegmatite-rich regions like Brazil, Madagascar, Pakistan, and the USA (California, Maine).
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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