gemstone
Black Agate
SiO2 (Cryptocrystalline Quartz)
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale, dark black to grey color, waxy to vitreous luster, microcrystalline quartz structure with no cleavage, and a specific gravity of 2.60 to 2.65.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, dark black to grey color, waxy to vitreous luster, microcrystalline quartz structure with no cleavage, and a specific gravity of 2.60 to 2.65.
Formation & geological history
Forms by the deposition of silica from groundwater in cavities of igneous and sedimentary rocks, often over millions of years.
Uses & applications
Widely used in jewelry, cabochons, rings, ornamental carvings, and holistic wellness practices.
Geological facts
Ancient civilizations used black agate as an amulet for protection and grounding. Its banded variety is one of the oldest known stones used in ornamentation.
Field identification & locations
Identified by its conchoidal fracture, smooth waxy polish, and high scratch resistance. Found globally, especially in Brazil, India, and the United States.
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