gemstone

Polished agate or chalcedony cabochon

Microcrystalline quartz (SiO₂), likely pale chalcedony/agate

AI-generated identification · may be incorrect

White-to-beige, smoothly polished dome with a waxy-to-vitreous luster and no visible cleavage; quartz hardness is about 7 Mohs and specific gravity about 2.6. The image does not show diagnostic banding or crystal structure clearly, so exact identification is uncertain.

Identified September 10, 2026More gemstone →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich fluids fill cavities and fractures, commonly in volcanic rocks; agate develops concentric or layered bands. Formation ages vary widely, from Paleozoic to recent deposits.

Uses & applications

Used for cabochons, carvings, beads, and small decorative objects; common polished pieces generally have modest value.

Geological facts

Its hemispherical shape and uniform polish indicate a cut-and-polished gemstone rather than a natural crystal face. It could also be another pale quartz variety or a polished stone composite.

Field identification & locations

Identify by its glassy/waxy surface, high hardness, and resistance to scratching by steel; true agate commonly shows translucent layers or banding when backlit. Common sources include Brazil, Uruguay, India, Madagascar, and the western United States.