mineral

Dyed and polished agate geode slice

Banded chalcedony, SiO₂, with a quartz-lined cavity

AI-generated identification · may be incorrect

Agate is microcrystalline quartz (Mohs 6.5–7), with waxy to vitreous luster and concentric bands; quartz crystals may line the center. The vivid blue-green colors appear enhanced by dye, and the cut, polished slice does not show natural cleavage.

Identified October 4, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited successive chalcedony layers in a cavity, commonly in volcanic rock; later quartz crystals may grow in the hollow. Agates form across many geological ages, and this photograph cannot establish the specimen’s age or locality.

Uses & applications

Primarily used as a decorative display piece, paperweight, or jewelry material; agate is also used for beads, cabochons, and ornamental objects.

Geological facts

Agate’s fine bands record changes in silica deposition. Dyeing is common in commercial agate slices and can produce unusually saturated colors.

Field identification & locations

Look for translucent silica, curved concentric bands, and a quartz-lined cavity; natural banding may be irregular, while strong uniform colors can indicate dye. Agates occur worldwide, including Brazil, Uruguay, and the United States.