gemstone

Polished carnelian agate

Chalcedony, microcrystalline quartz (SiO₂), colored mainly by iron oxides

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent orange, red-brown, and yellow bands with a waxy to vitreous luster. Quartz has a trigonal structure; chalcedony lacks visible cleavage and breaks conchoidally.

Identified September 27, 2026More gemstone →

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Physical properties

Mohs hardness 6.5–7; translucent orange, red-brown, and yellow bands with a waxy to vitreous luster. Quartz has a trigonal structure; chalcedony lacks visible cleavage and breaks conchoidally.

Formation & geological history

Forms as silica-rich fluids fill cavities and fractures, depositing microcrystalline quartz; iron compounds create its warm colors. Agates occur in rocks of many ages, commonly in volcanic environments.

Uses & applications

Used for beads, cabochons, carvings, and ornamental objects; durable pieces are popular in jewelry.

Geological facts

Carnelian is an orange-red variety of chalcedony, and the name is also often used loosely for similarly colored agate.

Field identification & locations

The image shows a smooth, polished orange chalcedony stone with cloudy banding, consistent with carnelian agate. Agate is found worldwide, notably in Brazil, India, Uruguay, and the United States; check for natural banding and avoid assuming color alone proves it is untreated.