gemstone

Carnelian (Polished Agate)

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on the Mohs scale. Color: Translucent reddish-orange to deep orange-red. Luster: Vitreous to waxy. Crystal structure: Trigonal (microcrystalline/cryptocrystalline quartz). Cleavage: None, exhibits conchoidal fracture.

Hardness: 6
Color: Translucent reddish-orange to deep orange-red
Luster: Vitreous to waxy

Identified July 26, 2026More gemstone →

Explore Carnelian (Polished Agate) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms at low temperatures in cavities of volcanic rocks (basalts and andesites) through silica-rich fluid deposition. Iron oxide impurities (hematite) impart the characteristic reddish-orange color.

Uses & applications

Used widely in jewelry (beads, cabochons, rings), decorative carvings, lapidary art, and as a popular tumbled gemstone for collectors.

Geological facts

Carnelian has been used in jewelry making for over 4,500 years. Ancient Romans used carnelian to create engraved signet rings for sealing documents, as hot wax does not stick to it.

Field identification & locations

Identified by its rich translucent orange-red hue, waxy finish, and smooth tumbled surface. Common in gravel deposits, riverbeds, and volcanic regions worldwide including the Western US.