mineral

Polished carnelian agate

Microcrystalline quartz (SiO₂), chalcedony with iron-oxide coloration

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange-red and white banding, vitreous to waxy luster, cryptocrystalline structure, and no visible cleavage. The rounded surface indicates tumbling or polishing.

Identified August 19, 2026More mineral →

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Physical properties

Hardness 6.5–7 Mohs; translucent orange-red and white banding, vitreous to waxy luster, cryptocrystalline structure, and no visible cleavage. The rounded surface indicates tumbling or polishing.

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing chalcedony and quartz in layers; iron oxides create the red-orange color. Most specimens formed in Cenozoic to older volcanic environments, though age varies by deposit.

Uses & applications

Used for cabochons, beads, carvings, decorative stones, and lapidary collections; durable enough for jewelry but generally not major construction aggregate.

Geological facts

The red variety is called carnelian, while the banded chalcedony is agate; mixed specimens are commonly marketed as carnelian agate.

Field identification & locations

Identify by translucent orange-red chalcedony, curved or irregular white bands, waxy luster, and lack of cleavage; it should resist scratching by steel. Common sources include Brazil, Uruguay, India, Madagascar, and the United States.