sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, translucent to opaque with banded or mottled color patterns including gray, brown, white, and red.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, translucent to opaque with banded or mottled color patterns including gray, brown, white, and red.
Formation & geological history
Formed primarily in cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions over millions of years.
Uses & applications
Used extensively in making jewelry, ornamental carvings, decorative objects, and historical precision instruments like mortar and pestle sets.
Geological facts
Agate is one of the most popular materials used in art and lapidary work. Ancient civilizations valued agates for amulets and seals, believing they could ward off thirst and protect against fevers.
Field identification & locations
Easily identified by its waxy luster, conchoidal fracture, and characteristic banding or translucent nodular shape. Frequently found in riverbeds, beaches, and weathered volcanic rock formations worldwide.
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