sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, colors range widely from white and gray to brown, blue, and red with distinctive banding patterns, specific gravity of 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, cryptocrystalline structure, colors range widely from white and gray to brown, blue, and red with distinctive banding patterns, specific gravity of 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 over long periods.
Uses & applications
Used extensively for ornamental objects, jewelry, decorative carvings, and in industrial applications such as mortars and pestles.
Geological facts
Agates are often found in ancient lava flows where gas bubbles previously existed, later filled by microscopic quartz crystals accumulating in rhythmic layers.
Field identification & locations
Easily identified by its conchoidal fracture, waxy luster, and characteristic concentric banding. Commonly found worldwide, especially in Brazil, the USA, and Germany.
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