mineral

Carnelian (Agate)

Carnelian (Silica, SiO2)

Hardness: 6.5-7 Mohs; Color: Brownish-red to orange; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: Brownish-red to orange
Luster: Vitreous to waxy

Identified July 1, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Brownish-red to orange; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed by the deposition of silica from groundwater in the cavities of igneous rocks such as basalt. The orange-red color comes from iron oxide impurities. Found in volcanic environments globally.

Uses & applications

Commonly used in jewelry, decorative carvings, and bead making. Historically used for signet rings and seals because hot wax does not stick to it.

Geological facts

Carnelian was highly valued in ancient civilizations; the Romans used it for seals, and the ancient Egyptians wore it in amulets for protection. Its color can often be enhanced or changed through heat treatment.

Field identification & locations

Identify in the field by its translucent body, waxy texture, and conchoidal fracture. Often found as pebbles in riverbeds or near ancient volcanic activity in locations like Brazil, India, and Madagascar.