Carnelian Agate (with Quartz/Chalcedony)

Physical Properties

Hardness: 6.5-7 on Mohs scale; Color: Reddish-brown, orange, white, and translucent gray; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64.

Formation & Geological History

Formed through the deposition of silica from groundwater in the cavities of igneous rocks, particularly volcanic lavas. The red-brown color is caused by iron oxide (hematite) impurities. These can range from millions to several hundred million years old.

Uses & Applications

Commonly used in jewelry, lapidary arts (cabochons and beads), decorative carvings, and as a popular specimen for rock collectors.

Geological Facts

Carnelian has been used as a gemstone since antiquity; it was highly prized by the Egyptians and Romans for cylinder seals and signet rings because hot wax does not stick to it.

Field Identification & Locations

Identify in the field by its waxy luster, translucency when held to light, and smooth, water-worn exterior if found in riverbeds. Often found in gravel deposits, volcanic regions, and coastal areas.

Identified on: 4/19/2026

Mode: Standard