mineral
Banded agate (chalcedony)
Agate, a banded variety of microcrystalline quartz (SiO₂)
AI-generated identification · may be incorrectCream to pale yellow, translucent, waxy-to-vitreous luster with curved bands; hardness 6.5–7 Mohs, trigonal quartz structure, no cleavage, specific gravity about 2.6. The small specimen appears naturally formed and possibly water-worn or polished.
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Physical properties
Cream to pale yellow, translucent, waxy-to-vitreous luster with curved bands; hardness 6.5–7 Mohs, trigonal quartz structure, no cleavage, specific gravity about 2.6. The small specimen appears naturally formed and possibly water-worn or polished.
Formation & geological history
Silica-rich groundwater deposited successive layers of chalcedony, commonly in cavities in volcanic rock; agates formed in many geological periods, from ancient to relatively recent.
Uses & applications
Used for beads, cabochons, carvings, ornaments, and some precision industrial components.
Geological facts
Agate banding records changes in silica deposition and trace impurities during growth.
Field identification & locations
Look for translucent chalcedony with curved or concentric bands and glass that it can scratch; common sources include Brazil, Uruguay, India, and the western United States. The photo alone cannot confirm its exact locality or whether it was polished.
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