mineral

Polished agate geode slice

Agate, a banded variety of microcrystalline quartz (SiO₂); likely quartz/chalcedony lining a geode

AI-generated identification · may be incorrect

Mostly white to translucent gray chalcedony with a dark outer rind and subtle banding. Quartz has Mohs hardness 7, vitreous-to-waxy luster, and a trigonal crystal structure; chalcedony is cryptocrystalline and lacks visible cleavage.

Identified September 24, 2026More mineral →

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Physical properties

Formation & geological history

Forms as silica-rich fluids fill cavities in volcanic rock, depositing chalcedony and quartz over time. The specimen’s geological age cannot be determined from the image.

Uses & applications

Polished slices are used for display, lapidary work, and jewelry; agate is also used for small ornamental objects.

Geological facts

Agate’s bands record successive mineral deposition, though the layering may be faint in pale specimens.

Field identification & locations

Look for a hard, waxy surface, translucent edges, and curved or concentric bands; geodes commonly occur in volcanic rocks. The image suggests a cut and polished specimen, but locality is unknown.