mineral
Banded Agate
Silicon Dioxide (SiO2) - Microcrystalline Quartz
AI-generated identification · may be incorrectHardness: 6.5 to 7 on the Mohs scale. Color: Translucent white, grey, beige, reddish-brown. Luster: Waxy to vitreous. Crystal Structure: Trigonal (microcrystalline/cryptocrystalline). Cleavage: None, exhibits conchoidal fracture.
- Hardness
- 6
- Color
- Translucent white, grey, beige, reddish-brown
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5 to 7 on the Mohs scale. Color: Translucent white, grey, beige, reddish-brown. Luster: Waxy to vitreous. Crystal Structure: Trigonal (microcrystalline/cryptocrystalline). Cleavage: None, exhibits conchoidal fracture.
Formation & geological history
Formed as a secondary mineral deposit in cavities within volcanic (igneous) rocks like basalt or rhyolite, created by silica-rich groundwater filling gas vesicles over millions of years.
Uses & applications
Used widely in lapidary arts, jewelry making, cabochon cutting, tumbled stones, ornamental carvings, and geological collections.
Geological facts
The distinctive fine parallel banding in agates represents successive layers of silica deposition. Some layers can be micro-porous, allowing agates to naturally absorb trace oxides or be artificially dyed.
Field identification & locations
Identified in the field by its characteristic concentric or parallel fine banding, translucent body, shell-like (conchoidal) fracture, and resistance to scratching by steel. Commonly found in Brazil, Uruguay, Lake Superior region (USA), Madagascar, and Scotland.
