mineral

Polished agate/geode slab

Banded chalcedony (microcrystalline quartz, SiO₂), likely with quartz crystals

AI-generated identification · may be incorrect

Mostly white to translucent gray with subtle bands and a rough crystalline area; quartz has Mohs hardness 7, vitreous-to-waxy luster, and no cleavage. The image does not show enough detail to confirm the exact variety or inclusions.

Identified September 24, 2026More mineral →

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Physical properties

Formation & geological history

Agate forms as silica-rich fluids deposit chalcedony in cavities, commonly in volcanic rocks; later cutting and polishing reveal the interior. The specimen’s geological age and source cannot be determined from the image.

Uses & applications

Decorative display, lapidary work, and jewelry; agate is also used for ornamental objects and, historically, precision components.

Geological facts

Agate is a variety of chalcedony, and geode interiors can combine banded material with quartz crystals.

Field identification & locations

Look for curved or concentric translucent bands and a hard, glassy surface; this piece appears cut and polished, so field identification is limited. Agates occur worldwide, including Brazil, Uruguay, India, and the western United States.