mineral

Polished agate pebble (likely dyed or naturally banded chalcedony)

Chalcedony, microcrystalline SiO₂; agate is banded chalcedony

AI-generated identification · may be incorrect

Smooth, rounded, polished pebble with a pale blue-gray outer area and dark purple-brown center; fine-grained, waxy to vitreous luster. Quartz hardness is about 6.5–7 Mohs, with no visible cleavage; the photo does not reveal crystal structure or confirm banding.

Identified September 23, 2026More mineral →

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Physical properties

Formation & geological history

Formed when silica-rich fluids filled cavities in volcanic rock and deposited successive layers of chalcedony; agates form in many geological periods. Color may be natural or enhanced by dyeing, which cannot be determined from the image.

Uses & applications

Used for jewelry, ornaments, and collecting; agate is also used for small ornamental objects and historically for precision components.

Geological facts

Agate’s characteristic bands record changing conditions during silica deposition. The pictured specimen is too small and visually indistinct to identify its variety confidently.

Field identification & locations

Check for curved or concentric bands, translucency at thin edges, and a waxy polish; a close-up or transmitted light would help distinguish agate from other polished stones. Agates occur worldwide, including Brazil, Uruguay, India, and the United States.