Carnelian (Red Chalcedony)

Physical Properties

Hardness: 6.5–7 on Mohs scale. Color: Translucent reddish-brown to orange-red. Luster: Vitreous to waxy. Crystal system: Trigonal (microcrystalline/cryptocrystalline). Specific gravity: 2.58–2.64.

Formation & Geological History

Formed in volcanic and sedimentary environments when silica-rich fluids permeate rock cavities (geodes) or veins. The reddish hue is caused by iron oxide impurities like hematite. It can be found in formations ranging from recent to hundreds of millions of years old.

Uses & Applications

Predominantly used as a gemstone in jewelry (rings, beads, pendants), as well as for decorative carvings, lapidary art, and historical cylinder seals and amulets.

Geological Facts

Carnelian was highly prized in ancient civilizations; it was found in the tombs of Egyptian pharaohs and was used by the Romans for signet rings because hot wax does not stick to it.

Field Identification & Locations

Identify by its translucent, waxy appearance and warm reddish-orange color. In the field, look for smooth, water-worn pebbles in riverbeds or within basaltic cavities in regions like Brazil, India, or Madagascar.

Identified on: 4/24/2026

Mode: Standard