Mineral

Carnelian Agate

Silicon Dioxide (SiO2) - variety Carnelian (Chalcedony)

Hardness: 6.5-7 on Mohs scale; Color: Translucent orange to reddish-brown; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline/cryptocrystalline); Cleavage: None; Specific Gravity: 2.58–2.64

Hardness: 6
Color: Translucent orange to reddish-brown
Luster: Vitreous to waxy

Identified March 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks. The orange color is caused by iron oxide impurities. These specimens are often hundreds of millions of years old and are frequently found as river-worn nodules.

Uses & applications

Commonly used in lapidary work, cabochon jewelry, beads, and as decorative pocket stones or carvings.

Geological facts

Carnelian was widely used in ancient Rome and Egypt for signet rings and amulets because wax does not stick to its smooth surface. It is often heat-treated commercially to enhance the red/orange saturation.

Field identification & locations

Identify in the field by its translucency when held to light, waxy texture, and lack of visible crystal faces. Common in gravel pits, riverbeds, and beaches, particularly in the Pacific Northwest (USA), Brazil, and India.

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