sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, variable colors due to impurities (red, brown, grey, white), waxy to vitreous luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, and specific gravity around 2.60 to 2.65.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, variable colors due to impurities (red, brown, grey, white), waxy to vitreous luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, and specific gravity around 2.60 to 2.65.
Formation & geological history
Formed primarily within cavities of volcanic and metamorphic rocks through the slow deposition of silica-rich groundwater solutions over millions of years.
Uses & applications
Used widely in ornamental objects, lapidary arts, jewelry, as well as industrial applications like precision mortars and pestles.
Geological facts
Agate is one of the most popular stones used in art and jewelry since antiquity, famously worked by the ancient Greeks and Romans for seals and signet rings.
Field identification & locations
Often identified by its characteristic concentric banding patterns and translucency. Commonly found in regions with historic volcanic activity worldwide.
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