mineral

Polished agate (likely carnelian or dyed red agate)

Chalcedony, microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent red to burgundy body with subtle banding, waxy-to-glassy luster, and no obvious cleavage. Specific gravity is about 2.6; the cut face appears polished and may be enhanced or dyed.

Identified August 26, 2026More mineral →

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Physical properties

Formation & geological history

Agate forms when silica-rich groundwater fills cavities in volcanic rocks, depositing chalcedony in successive layers. Formation commonly occurred during the Cenozoic or older volcanic episodes, depending on locality.

Uses & applications

Used for cabochons, carvings, ornaments, bookends, and lapidary display; good-quality natural pieces are used in jewelry.

Geological facts

Red color can result from iron oxides, while intensely uniform color may indicate dyeing or heat treatment. Agate is a variety of quartz rather than a separate mineral species.

Field identification & locations

Identify by hardness, translucent edges, waxy luster, and curved or concentric bands; common sources include Brazil, Uruguay, India, Madagascar, and Mexico. Avoid assuming vivid color is natural without testing or seller documentation.