gemstone

Polished carnelian agate

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

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange-red body with cream/gray chalcedony and possible agate banding; waxy to vitreous luster, cryptocrystalline structure, no visible cleavage, specific gravity about 2.6.

Identified August 19, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing chalcedony and iron-bearing layers; most specimens are Cenozoic to younger, though agates occur throughout geological time.

Uses & applications

Used for cabochons, carvings, beads, seals, and ornamental polished pieces; durable and relatively affordable jewelry material.

Geological facts

The vivid orange-red color commonly intensifies under transmitted light and results from dispersed hematite or limonite. The specimen appears cut and polished, exposing translucent chalcedony and contrasting host material.

Field identification & locations

Identify by its translucency, waxy texture, orange-red color, and hardness sufficient to scratch ordinary glass; agate commonly occurs as rounded nodules in basalt. Major sources include Brazil, Uruguay, India, Madagascar, and the United States.