mineral

Polished agate (likely carnelian/white agate)

Banded chalcedony, a microcrystalline variety of quartz (SiO₂)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent white, peach, and orange patches with a waxy-to-glassy polish. Trigonal quartz structure at microscopic scale; no visible cleavage, conchoidal fracture when broken; specific gravity about 2.6.

Identified October 13, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited chalcedony in cavities and fractures, commonly in volcanic rocks; the specimen has been shaped and polished. Agates form across many geological ages, often in Paleozoic-to-Cenozoic volcanic settings.

Uses & applications

Used for beads, cabochons, ornaments, and small decorative objects; also collected as a polished specimen.

Geological facts

Agate is chalcedony, not a single crystal, and its colors and bands reflect changes during silica deposition.

Field identification & locations

Look for translucent chalcedony, waxy luster, and curved or irregular color bands; common sources include Brazil, Uruguay, India, and the United States. A small polished piece like this is typically worth about $2–$15, depending on pattern and workmanship.