sedimentary
Banded Agate
Silicon Dioxide (SiO2) - Microcrystalline Quartz
AI-generated identification · may be incorrectHardness: 6.5-7 on Mohs scale. Color: Gray, black, and white bands. Luster: Vitreous to waxy. Texture: Smooth, likely water-worn or tumbled. Structure: Cryptocrystalline.
- Hardness
- 6
- Color
- Gray, black, and white bands
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale. Color: Gray, black, and white bands. Luster: Vitreous to waxy. Texture: Smooth, likely water-worn or tumbled. Structure: Cryptocrystalline.
Formation & geological history
Formed as a secondary deposit in volcanic rock cavities or sedimentary fissures where silica-rich fluids cooled and crystallized over thousands of years in distinctive layers.
Uses & applications
Used primarily in lapidary work for jewelry, decor, and as pocket stones for collectors. Often used for industrial burnishing due to its hardness.
Geological facts
Agate is named after the Achates River in Sicily where it was first discovered by ancient Greeks. Each band represents a different pulse of mineral-saturated fluid flow.
Field identification & locations
Look for distinctive, concentric or parallel banding and a waxy surface texture. This specific specimen’s rounded shape suggests it was weathered by water in a river or lacustrine environment.
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