mineral
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, translucent to opaque, waxy to vitreous luster, microcrystalline crystal structure, conchoidal fracture with no true cleavage, specific gravity of 2.58 to 2.64, typically exhibits banded colors ranging from clear, white, gray, brown, to red.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, translucent to opaque, waxy to vitreous luster, microcrystalline crystal structure, conchoidal fracture with no true cleavage, specific gravity of 2.58 to 2.64, typically exhibits banded colors ranging from clear, white, gray, brown, to red.
Formation & geological history
Formed primarily within cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions, often in concentric layers over millions of years.
Uses & applications
Used in jewelry, ornamental carvings, lapidary arts, precision instruments, and as specimen collectibles.
Geological facts
Agate was named by the Greek philosopher Theophrastus after the Achates river in Sicily where the stones were initially found.
Field identification & locations
Identified by its distinctive waxy luster, conchoidal fracture, and characteristic concentric banding. Commonly found worldwide in volcanic regions, river gravels, and ancient lava flows.
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