sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, varies in color with banded patterns, specific gravity of 2.58-2.64.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, varies in color with banded patterns, specific gravity of 2.58-2.64.
Formation & geological history
Formed mainly within cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions over millions of years.
Uses & applications
Used in jewelry, ornaments, carvings, and industrial applications such as mortar and pestle sets due to its hardness.
Geological facts
Agate has been used since ancient times for talismans and ornamentation, famously carved into intricate signet rings in ancient Greece and Rome.
Field identification & locations
Found worldwide in volcanic rock cavities and gravel riverbeds; easily identified in the field by its distinct concentric banding and waxy luster.
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