Carnelian Agate

Physical Properties

Hardness: 6.5-7 (Mohs); Color: Red-orange to brownish-red; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None; 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 tint is caused by iron oxide (hematite) impurities.

Uses & Applications

Primarily used in jewelry (beads, cabochons), carvings, decorative seals, and as a collector's stone. Historically used for signet rings.

Geological Facts

Carnelian was highly prized by Ancient Egyptians, who believed it had protective powers; it was also used by Roman and Greek civilizations for intaglio seals because wax does not stick to it.

Field Identification & Locations

Identified in the field by its translucent appearance, waxy luster, and distinctive orange-red hue. Commonly found in riverbeds or coastal areas where volcanic rock has eroded, notably in India, Brazil, and Uruguay.

Identified on: 4/17/2026

Mode: Standard