mineral

Polished agate slice

Agate, a banded variety of chalcedony (microcrystalline quartz, SiO₂)

AI-generated identification · may be incorrect

Translucent cream, gray, and tan concentric bands with a polished surface and rough outer rind. Quartz hardness is about 6.5–7 Mohs; trigonal crystal structure, waxy-to-vitreous luster, and no cleavage. Specific gravity is about 2.6.

Identified October 10, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich fluids deposited successive layers in a cavity, commonly in volcanic rock; later polishing exposed the bands. Agates form in many geological ages and settings.

Uses & applications

Used for ornaments, cabochons, beads, bookends, and decorative slices; this specimen is primarily decorative.

Geological facts

Agate’s bands record changes in the chemistry or conditions of silica deposition, though visible patterns alone do not establish a precise origin.

Field identification & locations

The concentric banding and quartz-like hardness are characteristic; agate occurs worldwide, often in volcanic rocks and stream gravels. The pictured slice may have been cut and polished, and its exact locality cannot be determined visually.