Carnelian Agate

Physical Properties

Hardness: 6.5–7 (Mohs scale); Color: Orange to reddish-brown; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal) microcrystalline; Cleavage: None; Specific gravity: 2.58–2.64

Formation & Geological History

Formed in low-temperature hydrothermal environments where silica-rich fluids deposit in cavities (vesicles) within volcanic rocks. The orange color is derived from iron oxide impurities.

Uses & Applications

Primarily used in jewelry (beads, cabochons), carvings, intaglios, and as a popular specimen for collectors.

Geological Facts

Carnelian was highly valued in ancient civilizations; the Romans used it for signet rings because hot wax does not stick to it. It has been used as a gemstone for over 4,500 years.

Field Identification & Locations

Identify by its translucent reddish-orange hue and waxy luster. In the field, look for nodules in basalt or as water-worn pebbles in riverbeds. These are common in Brazil, India, and Uruguay.

Identified on: 4/13/2026

Mode: Standard