gemstone

Polished agate cabochon or carved chalcedony

Microcrystalline quartz (SiO₂), likely brown/orange chalcedony or agate

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent brown, honey, and cream coloration with waxy to vitreous luster. It appears polished and possibly carved, with no obvious cleavage and a fine cryptocrystalline quartz structure.

Identified September 5, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing chalcedony and sometimes iron oxides in layers. Agate formation commonly occurred during the Cenozoic, though specimens can be much older depending on the host rock.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and small jewelry pieces; polished agate is also collected for its banding and color.

Geological facts

The visible brown tones are commonly caused by iron oxides or hydroxides. Chalcedony is quartz composed of microscopic interlocking fibers rather than large visible crystals.

Field identification & locations

Identify by its glassy-to-waxy polish, translucency, quartz hardness, and lack of cleavage; a steel file should not scratch it easily. Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States.