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, specific gravity around 2.60 to 2.65, translucent to opaque with distinct color banding.
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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, specific gravity around 2.60 to 2.65, translucent to opaque with distinct color banding.
Formation & geological history
Formed primarily within the cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater circulating in solutions, often over millions of years.
Uses & applications
Commonly used in making jewelry, ornamental carvings, polished display specimens, mortar and pestles for laboratory use, and by collectors.
Geological facts
Agate is one of the most popular and varied stones used in lapidary arts. Ancient civilizations valued agates for their amulets and healing properties, believing they could ward off thirst and protect against fevers.
Field identification & locations
Easily identified by its distinctive concentric banding and waxy luster when wet or polished. Often found in riverbeds, beaches, and eroded volcanic regions worldwide.
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