mineral
Banded Agate (Gray Agate)
Silicon Dioxide (SiO2) - Variety of Chalcedony
AI-generated identification · may be incorrectHardness: 6.5-7 Mohs; Color: Gray, black, white concentric bands; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64
- Hardness
- 6
- Color
- Gray, black, white concentric bands
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Gray, black, white concentric bands; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64
Formation & geological history
Formed through the deposition of silica from groundwater in the cavities (vesicles) of igneous rocks, particularly basaltic lava flows. The bands are formed by repeated layers of mineral deposition over thousands of years.
Uses & applications
Primarily used for lapidary arts, jewelry (cabochons), carvings, and as a decorative or metaphysical stone.
Geological facts
The banding in agate is caused by changes in the chemical composition of the silica-rich fluids during formation. This specific specimen has been carved and polished into a crescent moon shape.
Field identification & locations
Identify in the field by its waxy luster, conchoidal fracture, and characteristic banding. Often found in riverbeds or volcanic regions like Brazil, Botswana, or India.
