sedimentary
Agate
Silicon dioxide (Chalcedony), SiO2
Hardness: 6.5-7 on the Mohs scale, Color: Brownish, translucent with banded inclusions, Luster: Waxy to vitreous, Crystal structure: Trigonal (microcrystalline quartz)
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 on the Mohs scale, Color: Brownish, translucent with banded inclusions, Luster: Waxy to vitreous, Crystal structure: Trigonal (microcrystalline quartz)
Formation & geological history
Formed by the deposition of silica from groundwater in the cavities of igneous and sedimentary rocks over millions of years.
Uses & applications
Used primarily in jewelry, ornamental carvings, polished specimens, and collection displays.
Geological facts
Agate is a variety of chalcedony and often forms in ancient volcanic vesicles, creating unique concentric banding patterns.
Field identification & locations
Can be identified in the field by its waxy luster, conchoidal fracture, and characteristic translucent banding when held to the light. Commonly found globally in volcanic rock cavities and river gravels.
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