gemstone
Black Onyx
Silicon dioxide (SiO2) / Cryptocrystalline quartz
AI-generated identification · may be incorrectHardness of 6.5-7 on the Mohs scale, vitreous to waxy luster, trigonal crystal system (microcrystalline), opaque black color.
Identified More gemstone →
Explore Black Onyx in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness of 6.5-7 on the Mohs scale, vitreous to waxy luster, trigonal crystal system (microcrystalline), opaque black color.
Formation & geological history
Formed in gas cavities of volcanic lavas through the deposition of silica; commonly treated or dyed chalcedony in commercial jewelry.
Uses & applications
Extensively used in fine jewelry such as cabochons, rings, and earrings, as well as hardstone carvings and cameos.
Geological facts
Natural solid black onyx is extremely rare; almost all commercial black onyx has been chemically stained or heat-treated since ancient Roman times.
Field identification & locations
Identified by its high polish, smooth waxy-to-vitreous sheen, uniform deep black tone, and scratch resistance to steel needles.
More like this
Other gemstone specimens
Ammolite
Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)
mineral
Gemstone Ring
N/A - Set piece of jewelry, likely Amethyst or Garnet with Diamond or CZ
gemstone
Amber
Succinite (Organic Gemstone)
mineral
Red Jasper
Silicon Dioxide (SiO2) with Hematite inclusions
sedimentary
Diamond and Gold Jewelry
Carbon (Diamond) / Au (Gold)
gemstone
Cubic Zirconia (simulant) or Diamond
ZrO2 (Cubic Zirconia) or C (Diamond)
gemstone