mineral

Carnelian Agate

Silicon Dioxide (SiO2) - variety of Chalcedony

Hardness: 6.5-7 (Mohs scale), Color: Amber, orange-red, to brown, Luster: Waxy to vitreous, Crystal Structure: Trigonal (microcrystalline/cryptocrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.58-2.64

Hardness: 6

Identified May 10, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater into cavities of igneous rocks, particularly volcanic lavas. The reddish-orange color is caused by iron oxide (hematite) impurities.

Uses & applications

Primarily used for lapidary work, jewelry (beads, cabochons, signet rings), and as architectural accents or ornamental objects.

Geological facts

Carnelian has been used as a gemstone since the Neolithic period. The Romans used it extensively for signet rings because hot wax does not stick to it.

Field identification & locations

Identify by its characteristic waxy luster, translucency, and warm orange hue. It is commonly found in Brazil, India, Uruguay, and the United States (notably Oregon and Washington). In the field, look for translucent orange stones with smooth, water-worn surfaces.

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