sedimentary
Black Agate
Chalcedony (SiO2)
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, displays striking concentric banding in shades of black, gray, and white.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, displays striking concentric banding in shades of black, gray, and white.
Formation & geological history
Formed through the deposition of silica-rich groundwater within cavities of volcanic or sedimentary rocks over millions of years.
Uses & applications
Widely used for ornamental carvings, polished display specimens, lapidary art, and jewelry making.
Geological facts
Agate bands represent successive layers of microscopic quartz crystals deposited from mineral solutions over long geological periods.
Field identification & locations
Easily identified by its distinctive concentric color banding and waxy luster; found globally in volcanic regions.
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