sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline crystal structure, distinct micro-banded patterns, colors range widely including white, grey, blue, violet, and brown, specific gravity around 2.60 to 2.65.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline crystal structure, distinct micro-banded patterns, colors range widely including white, grey, blue, violet, and brown, specific gravity around 2.60 to 2.65.
Formation & geological history
Formed mainly in cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions, often layer by layer over millions of years.
Uses & applications
Used primarily in jewelry, ornamental carvings, polished specimens, decorative objects, and occasionally in industrial precision instruments.
Geological facts
Agate is one of the most popular gemstones used in lapidary arts. The bands in an agate reflect changes in the water chemistry or mineral content during its formation.
Field identification & locations
Can be identified in the field by its characteristic waxy luster, conchoidal fracture, and concentric color banding. Commonly found in regions with volcanic activity worldwide.
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