gemstone
Agate
Silicon dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, typically multicolored or banded, waxy to vitreous luster, microcrystalline crystal structure, conchoidal fracture with no cleavage, specific gravity of 2.60 to 2.65.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, typically multicolored or banded, waxy to vitreous luster, microcrystalline crystal structure, conchoidal fracture with no cleavage, specific gravity of 2.60 to 2.65.
Formation & geological history
Formed mainly in cavities of volcanic and metamorphic rocks by the deposition of silica from groundwater solutions in concentric layers over millions of years.
Uses & applications
Widely used in jewelry, ornamental carvings, polished display specimens, and industrial applications requiring durable precision bearings or mortars.
Geological facts
Agate is one of the most common materials used in the art of lapidary and has been valued as an amulet and ornament since antiquity, notably in ancient Greece and Egypt.
Field identification & locations
Easily identified by its distinctive banded patterns and translucent quality. Found globally, especially in volcanic regions, Brazil, and parts of the United States.
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