sedimentary
Agate Nodule
Silicon Dioxide (Chalcedony), SiO2
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale. Varies in color from brown and red to grey, featuring a waxy to vitreous luster and a microcrystalline or cryptocrystalline crystal structure with no visible cleavage.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale. Varies in color from brown and red to grey, featuring a waxy to vitreous luster and a microcrystalline or cryptocrystalline crystal structure with no visible cleavage.
Formation & geological history
Formed through the deposition of silica-rich groundwater solutions in cavities of ancient volcanic and sedimentary rocks over millions of years.
Uses & applications
Widely used in lapidary arts, decorative items, jewelry making, and sought after by mineral collectors.
Geological facts
Agate bands record ancient chemical fluctuations in the groundwater that created them. Famous deposits occur worldwide, notably in Brazil, Madagascar, and the US.
Field identification & locations
Identify in the field by its conchoidal fracture, waxy luster, and concentric banding or botryoidal surface texture. Commonly found in riverbeds and eroded volcanic regions.
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