mineral
Black Onyx
Chalcedony (SiO2) with parallel banding
AI-generated identification · may be incorrectHardness: 6.5-7 (Mohs), Color: Black with white bands, Luster: Vitreous to waxy, Crystal structure: Trigonal/Monoclinic (Cryptocrystalline), Cleavage: None, Specific gravity: 2.65-2.67
- Hardness
- 6
Identified More mineral →
Explore Black Onyx in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 (Mohs), Color: Black with white bands, Luster: Vitreous to waxy, Crystal structure: Trigonal/Monoclinic (Cryptocrystalline), Cleavage: None, Specific gravity: 2.65-2.67
Formation & geological history
Formed by the deposition of silica in gas cavities (vesicles) in volcanic lava flows; the bands result from rhythmic crystallization and varied mineral impurities over time.
Uses & applications
Extensively used in jewelry (rings, beads, pendants), ornamental carvings, and decorative items due to its durability and aesthetic banding.
Geological facts
Unlike agate, which has curved bands, onyx is defined by having parallel bands; it has been used since antiquity for intaglio and cameo engravings.
Field identification & locations
Identified by its distinctive black-and-white parallel stripes and waxy luster when polished. Commonly sourced from Brazil, India, and Madagascar; can be distinguished from obsidian by its higher hardness and internal banding.
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
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