mineral

Polished banded agate

Agate, a banded variety of chalcedony (microcrystalline SiO₂)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; waxy to vitreous luster, translucent white-gray and reddish-brown bands, cryptocrystalline quartz structure. The small polished surface limits identification certainty.

Identified October 7, 2026More mineral →

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Physical properties

Hardness 6.5–7 Mohs; waxy to vitreous luster, translucent white-gray and reddish-brown bands, cryptocrystalline quartz structure. The small polished surface limits identification certainty.

Formation & geological history

Forms as silica-rich groundwater deposits concentric or irregular chalcedony layers in cavities, commonly in volcanic rocks. Agates formed in many geologic periods; age cannot be determined from the image.

Uses & applications

Used for jewelry, beads, ornaments, and collecting; agate is also used for decorative objects and precision components.

Geological facts

Agate’s banding records successive changes in silica deposition and impurities; iron compounds commonly create red and brown colors.

Field identification & locations

Look for fine, curved bands and a glassy-to-waxy surface; common sources include Brazil, Uruguay, India, and the United States. A small polished piece like this typically sells for about $1–$10.