sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, exhibits vibrant orange, white, and translucent colors with a waxy to vitreous luster, cryptocrystalline structure, no true cleavage, and a specific gravity around 2.60 to 2.65.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, exhibits vibrant orange, white, and translucent colors with a waxy to vitreous luster, cryptocrystalline structure, no true cleavage, and a specific gravity around 2.60 to 2.65.
Formation & geological history
Formed through the deposition of silica from groundwater in the cavities of ancient rocks, typically volcanic or sedimentary, over millions of years.
Uses & applications
Commonly used in making jewelry, ornamental carvings, decorative objects, and as collector specimens.
Geological facts
Agates are often found lining or filling cavities in volcanic rocks called geodes, and the distinct banding patterns represent successive layers of microscopic quartz crystals deposited over long periods.
Field identification & locations
Easily identified by its characteristic concentric color bands, waxy luster, and translucent quality when held up to the light. Found globally in riverbeds, beaches, and volcanic regions.
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