sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, microcrystalline crystal structure, conchoidal fracture with no true cleavage, and specific gravity around 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, microcrystalline crystal structure, conchoidal fracture with no true cleavage, and specific gravity around 2.58 to 2.64.
Formation & geological history
Formed primarily within cavities of volcanic and metamorphic rocks through the deposition of silica-rich groundwater solutions in concentric layers over geological time.
Uses & applications
Commonly used in ornamental carvings, jewelry, lapidary art, and precision instruments like mortar and pestles.
Geological facts
Agate is one of the most popular stones used in ancient lapidary arts, with artifacts dating back to the Neolithic period in Greece and the Indus Valley Civilization.
Field identification & locations
Identified by its distinct concentric banding patterns, waxy luster, and resistance to scratching by steel. Found globally, notably in Brazil, Uruguay, India, Madagascar, and the United States.
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