sedimentary
Agate
Silicon dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, conchoidal fracture, variable colors including brown, grey, blue, and white arranged in concentric bands.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, conchoidal fracture, variable colors including brown, grey, blue, and white arranged in concentric bands.
Formation & geological history
Formed by the deposition of silica from groundwater in the cavities of igneous or sedimentary rocks, often over millions of years during various geological periods.
Uses & applications
Used primarily in lapidary arts, ornamental objects, jewelry, and as collector specimens.
Geological facts
Agate is one of the most popular gemstones used in history, often found lining or filling geodes and volcanic vesicles.
Field identification & locations
Identified easily by its waxy luster, conchoidal fracture, and distinct banding patterns. Found worldwide in volcanic rock cavities.
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