sedimentary
Agate
Silicon dioxide (Chalcedony), SiO2
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale, waxy luster, and conchoidal fracture. Displays distinct translucent banding patterns in various colors.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy luster, and conchoidal fracture. Displays distinct translucent banding patterns in various colors.
Formation & geological history
Forms by the deposition of silica from groundwater in cavities of igneous and sedimentary rocks. Typically develops over millions of years in volcanic vesicles.
Uses & applications
Widely used in jewelry, ornamental carvings, polished specimens, and precision instruments.
Geological facts
Agate was highly prized in ancient civilizations as a talisman and for creating intricate carved cameos. It is named after the Achates River in Sicily.
Field identification & locations
Identified by its waxy luster, hardness, and characteristic concentric banding. Commonly found globally in volcanic rock cavities and river gravels.
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