mineral

Tumbled carnelian agate

Microcrystalline quartz (chalcedony), SiO₂, colored mainly by iron oxides

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; orange-red and whitish-gray patches, waxy to vitreous luster, cryptocrystalline structure, no visible cleavage, and specific gravity about 2.6. The rounded, polished form indicates tumbling and surface wear.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rocks, depositing chalcedony and iron-bearing layers; coloration develops through oxidation. Agates commonly formed during the Cenozoic and Mesozoic, although older examples occur.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; durable aggregate-quality material has minor industrial use. This small tumbled specimen is primarily a low-cost collector or craft stone.

Geological facts

Carnelian is the orange-red variety of chalcedony, while banded or multicolored material is generally called agate. Heat treatment can intensify its red-orange color.

Field identification & locations

Identify it by its translucent orange-red chalcedony, waxy polish, very fine texture, and hardness sufficient to scratch glass; gray-white areas may be quartz or pale chalcedony. Common sources include Brazil, Uruguay, India, Madagascar, and the United States.