mineral

Carnelian (Red Chalcedony)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Orangey-red to brownish-red; Luster: Waxy to vitreous; Crystal Structure: Trigonal (Microcrystalline); Cleavage: None; Fracture: Conchoidal.

Hardness: 6
Color: Orangey-red to brownish-red
Luster: Waxy to vitreous

Identified July 5, 2026More mineral →

Explore Carnelian (Red Chalcedony) in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Orangey-red to brownish-red; Luster: Waxy to vitreous; Crystal Structure: Trigonal (Microcrystalline); Cleavage: None; Fracture: Conchoidal.

Formation & geological history

Forms through the deposition of silica from groundwater into cavities of igneous rocks. Its red color comes from iron oxide (hematite) impurities. It can be found in volcanic environments and ancient sedimentary gravel beds.

Uses & applications

Extensively used for jewelry, lapidary cabochons, seals, and ornamental carvings. Historically used for signet rings and amulets.

Geological facts

Carnelian is one of the oldest known gemstones, used for thousands of years in ancient Mesopotamia and Egypt. It was believed by ancient Romans to represent courage.

Field identification & locations

Identified by its distinctive translucency and waxy surface when broken. Common locations include Brazil, India, Uruguay, and various parts of the United States like the Pacific Northwest. Collectors look for uniform color and high translucency.