gemstone

Tumbled carnelian agate

Microcrystalline quartz (chalcedony), SiO₂, iron-oxide colored

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange-red to reddish brown with curved cream banding, vitreous/waxy luster, and no visible cleavage. Its concentric bands indicate agate; the orange color comes from dispersed hematite or limonite.

Identified August 29, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing successive chalcedony layers; iron impurities produce the red-orange color. Most specimens are Cenozoic to older, depending on the host lava and locality.

Uses & applications

Commonly cut and polished into cabochons, beads, pendants, and carvings; also used as a lapidary and ornamental stone. It has modest commercial value but attractive banding increases desirability.

Geological facts

Carnelian is the red-orange variety of chalcedony, while banded material is often marketed as carnelian agate. Heat treatment can intensify pale chalcedony into stronger orange-red tones.

Field identification & locations

Identify it by its smooth polish, translucency, waxy luster, curved bands, and resistance to scratching by steel; glass should not scratch it readily. Common sources include Brazil, Uruguay, India, Madagascar, and Germany.