mineral

Polished agate or chalcedony pebble

Microcrystalline quartz (SiO₂), likely agate/chalcedony

AI-generated identification · may be incorrect

The small, rounded specimen has a glossy, pale yellow-brown exterior and a dark brown-black patch; fine banding is not clearly visible. Quartz hardness is about 7 Mohs, with a vitreous to waxy luster and no cleavage; exact identification is limited by the image.

Identified October 10, 2026More mineral →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich fluids deposit quartz in cavities and fractures, often in volcanic rocks; agate may develop during repeated deposition. Its age and locality cannot be determined from the image.

Uses & applications

Polished chalcedony is used in beads, jewelry, ornaments, and collections.

Geological facts

Agate is a banded variety of chalcedony, while chalcedony without obvious bands may be sold under that broader name.

Field identification & locations

A hard, glassy surface and conchoidal fracture support quartz identification; distinctive internal bands would favor agate. The image does not show enough detail to confirm the dark patch or precise variety.