mineral
Black Tourmaline (Schorl) or Black Obsidian
Complex borosilicate (Schorl: NaFe3Al6(BO3)3Si6O18(OH)4) or Volcanic Glass (Obsidian: ~70-75% SiO2)
AI-generated identification · may be incorrectHardness 5-7.5, opaque jet black color, vitreous to resinous luster, conchoidal to uneven fracture.
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Physical properties
Hardness 5-7.5, opaque jet black color, vitreous to resinous luster, conchoidal to uneven fracture.
Formation & geological history
Formed through rapid cooling of felsic lava (obsidian) or crystallized within granitic pegmatites and metamorphic veins (tourmaline).
Uses & applications
Commonly shaped into tumbled pocket stones, meditation cubes, and cabochons for jewelry or ornamental crafts.
Geological facts
Shaped stone cubes like this are popular in crystal healing traditions, often marketed as protective stones to repel negative energy.
Field identification & locations
Identifiable by its smooth polished surfaces, cubic carving, uniform black hue, and vitreous reflection under indoor light.
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Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Limonite
FeO(OH)•nH2O
mineral
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