gemstone

Tumbled carnelian

Carnelian, a red-orange cryptocrystalline chalcedony (SiO₂)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent reddish-brown color, waxy to vitreous luster, and no visible crystals or cleavage. Color comes mainly from iron-oxide inclusions; specific gravity is about 2.58–2.64.

Identified August 16, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron staining producing red to orange tones; commonly associated with volcanic rocks and Cenozoic to older deposits. This specimen is polished/tumbled, obscuring its original matrix.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; generally inexpensive but attractive material for jewelry and lapidary work.

Geological facts

Carnelian is a variety of chalcedony, itself a microcrystalline form of quartz. Natural color may intensify after gentle heating or exposure to iron-rich solutions.

Field identification & locations

Identify it by its smooth polish, semitranslucent warm red color, glassy-waxy luster, and lack of cleavage; a scratch test should not be attempted on the specimen. Common sources include India, Brazil, Uruguay, Madagascar, and parts of the United States.