sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, colors vary widely including white, grey, blue, green, and yellow, specific gravity of 2.58 to 2.64.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, colors vary widely including white, grey, blue, green, and yellow, specific gravity of 2.58 to 2.64.
Formation & geological history
Forms primarily within cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions, often in concentric bands.
Uses & applications
Used widely in ornamental objects, jewelry, decorative carvings, and in industrial applications such as mortar and pestle sets due to its hardness.
Geological facts
Agate is one of the most common materials used in the art of lapidary and has been used since ancient times for amulets and seals.
Field identification & locations
Can be identified in the field by its characteristic waxy luster and banded patterns within nodules; commonly found in volcanic rock cavities worldwide.
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