mineral
Banded agate (polished/tumbled)
Microcrystalline quartz, SiO₂; likely banded chalcedony
AI-generated identification · may be incorrectWaxy to vitreous luster with parallel cream, gray-green, and brown bands. Quartz hardness is about 6.5–7 Mohs; trigonal crystal structure, no visible cleavage, and specific gravity around 2.6.
Identified More mineral →
Explore Banded agate (polished/tumbled) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Waxy to vitreous luster with parallel cream, gray-green, and brown bands. Quartz hardness is about 6.5–7 Mohs; trigonal crystal structure, no visible cleavage, and specific gravity around 2.6.
Formation & geological history
Silica-rich groundwater deposited successive layers in a cavity, later lithified and polished; agate deposits occur in rocks of many ages, commonly in volcanic regions.
Uses & applications
Used for jewelry, carvings, ornaments, and collectible specimens; agate has also been used for small precision instruments.
Geological facts
Agate’s distinctive bands record changing mineral conditions during growth; colors may be enhanced by dyeing or other treatment.
Field identification & locations
Identify by its fine, curved or parallel bands and hardness sufficient to scratch glass; common sources include Brazil, Uruguay, India, and the western United States.
