sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, crypto-crystalline structure, specific gravity of 2.60 to 2.65, displays distinct concentric banding in various colors.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, conchoidal fracture, crypto-crystalline structure, specific gravity of 2.60 to 2.65, displays distinct concentric banding in various colors.
Formation & geological history
Formed mainly in cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions over millions of years.
Uses & applications
Used in jewelry, decorative ornaments, lapidary art, precision instruments, and mortar and pestle sets due to its hardness.
Geological facts
Agate was named by Theophrastus, a Greek philosopher, after the Achates River in Sicily where the stones were first found.
Field identification & locations
Found worldwide, often in volcanic regions, riverbeds, and gravel deposits. Identify by its characteristic banded patterns and waxy luster.
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