gemstone

Carnelian Agate

Silicon Dioxide (SiO2)

Hardness of 6.5 to 7 on the Mohs scale, orange to reddish-brown color, waxy to vitreous luster, microcrystalline (cryptocrystalline) trigonal/hexagonal crystal structure, no true cleavage, specific gravity of 2.58 to 2.64.

Identified August 5, 2026More gemstone →

Explore Carnelian 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 in cavities of pre-existing rocks, typically volcanic or sedimentary environments, through the slow deposition of silica-rich groundwater over millions of years.

Uses & applications

Commonly used in jewelry, cabochons, beads, ornamental carvings, and as a popular tumbled stone for collectors and metaphysical uses.

Geological facts

Carnelian has been prized since ancient times, frequently used in ancient Rome for signet rings to seal documents because hot wax does not stick to it.

Field identification & locations

Easily identified by its translucent orange-to-red hue and banded agate patterns when backlit; widely found worldwide including Brazil, India, Uruguay, and the United States.