sedimentary
Agate
Silicon dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, colors vary widely including red, brown, white, gray, and blue, luster is waxy to vitreous, cryptocrystalline structure, conchoidal fracture with no true cleavage.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, colors vary widely including red, brown, white, gray, and blue, luster is waxy to vitreous, cryptocrystalline structure, conchoidal fracture with no true cleavage.
Formation & geological history
Formed mainly in cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions, often in concentric bands.
Uses & applications
Used for ornamental objects, jewelry, polished specimens, and in industrial applications requiring wear resistance.
Geological facts
Agates are often named after the localities where they are found, such as Lake Superior Agates or Botswana Agates, and have been used for millennia in talismans and ornamentation.
Field identification & locations
Can be identified in the field by its waxy luster, concentric banding, and translucent edges. Found worldwide, particularly in regions with past volcanic activity.
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