mineral
Polished Black Onyx (or Obsidian)
Silicon Dioxide (SiO2)
Mohs hardness 6.5-7 for Onyx (5-5.5 for Obsidian); deep black color; vitreous (glassy) luster; no cleavage; conchoidal fracture.
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Physical properties
Mohs hardness 6.5-7 for Onyx (5-5.5 for Obsidian); deep black color; vitreous (glassy) luster; no cleavage; conchoidal fracture.
Formation & geological history
Onyx forms in quartz veins or cavities in igneous rocks as silica-rich fluids deposit layers. Obsidian forms when high-silica lava cools rapidly above ground.
Uses & applications
Used extensively in jewelry making, ornamental carvings, polished cabochons, and crystal healing collections.
Geological facts
Black onyx is historically associated with protection and grounding energy, while natural obsidian is volcanic glass used anciently for ultra-sharp blades and arrows.
Field identification & locations
Identified by its rich glossy black finish, high polish, and smooth texture. Commonly found in Brazil, India, Madagascar, and various volcanic regions worldwide.
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