sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, color ranges from greyish-white with banding to translucent brownish tones, waxy to vitreous luster, cryptocrystalline crystal structure (microscopic quartz fibers), conchoidal fracture, specific gravity of 2.58 to 2.64.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, color ranges from greyish-white with banding to translucent brownish tones, waxy to vitreous luster, cryptocrystalline crystal structure (microscopic quartz fibers), conchoidal fracture, specific gravity of 2.58 to 2.64.
Formation & geological history
Formed primarily within cavities of volcanic and metamorphic rocks through the deposition of silica-rich groundwater solutions in concentric layers over long geological periods.
Uses & applications
Commonly used for making decorative items, jewelry, carvings, stone tumbling, and in industrial applications requiring wear resistance.
Geological facts
Agate was named by Theophrastus, a Greek philosopher and naturalist, who discovered the stone along the shoreline of the Achates River in Sicily.
Field identification & locations
Easily identified in the field by its distinct concentric banding, waxy texture, and conchoidal fracture. Found worldwide, particularly in regions with historical volcanic activity.
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