sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, concoidal fracture, specific gravity around 2.60 to 2.65, often displays distinctive multicolored banding.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, concoidal fracture, specific gravity around 2.60 to 2.65, often displays distinctive multicolored banding.
Formation & geological history
Formed mainly in cavities of volcanic and metamorphic rocks through the deposition of silica-rich groundwater solutions over long periods.
Uses & applications
Used in jewelry, decorative ornaments, mortars and pestles for laboratory work, and by mineral collectors.
Geological facts
Agates are named after the Achates River in Sicily where they were found in ancient times. They often form in ancient gas bubbles in volcanic lava.
Field identification & locations
Can be identified by its distinctive concentric banding and waxy luster. Common in regions with volcanic activity and river gravel beds worldwide.
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