mineral
Black Onyx
Chalcedony (SiO2)
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale, solid black color, waxy to vitreous luster, and cryptocrystalline crystal structure with no cleavage.
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 of 6.5 to 7 on the Mohs scale, solid black color, waxy to vitreous luster, and cryptocrystalline crystal structure with no cleavage.
Formation & geological history
Formed through the deposition of silica in gas cavities of lava or in fractures of existing rocks, often during hydrothermal activity.
Uses & applications
Commonly used in jewelry, carvings, cameos, and as a protective metaphysical talisman.
Geological facts
Ancient Greeks and Romans used black onyx to create intricate intaglio rings and seals due to its fine-grained layering.
Field identification & locations
Identified by its deep opaque black color, conchoidal fracture, and ability to take a high polish; found worldwide including Brazil, India, and the USA.
