sedimentary
Agate
Silicon dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, specific gravity of 2.58 to 2.64, featuring concentric banding in various colors.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, specific gravity of 2.58 to 2.64, featuring concentric banding in various colors.
Formation & geological history
Formed primarily within cavities of volcanic and metamorphic rocks through the deposition of silica-rich groundwater solutions over millions of years.
Uses & applications
Used in ornamental objects, jewelry, carvings, display specimens, and historically in precision instruments like mortar and pestle sets.
Geological facts
Agate has been used since ancient times (dating back to the Neolithic period) for seals, beads, and talismans, named after the Achates River in Sicily.
Field identification & locations
Easily identified by its distinctive banded patterns and waxy luster; commonly found in riverbeds, glacial tills, and volcanic regions worldwide.
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