sedimentary
Agate
Silicon dioxide (Chalcedony variety)
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, banded or concentric appearance, cryptocrystalline structure, no cleavage, specific gravity of 2.58 to 2.64.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, banded or concentric appearance, cryptocrystalline structure, no cleavage, specific gravity of 2.58 to 2.64.
Formation & geological history
Formed mainly in cavities of volcanic and metamorphic rocks through the deposition of silica-rich groundwater over long periods, often over millions of years.
Uses & applications
Commonly used in jewelry, ornamental carvings, decorative objects, and as a collector's specimen.
Geological facts
Agate is one of the most popular and varied gemstones known, named after the Achates River in Sicily where they were found in ancient times.
Field identification & locations
Easily identified by its distinctive banded patterns and translucent quality. Found globally in volcanic regions, riverbeds, and gravel deposits.
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