gemstone

Orange chalcedony (carnelian), likely tumbled fragment

Cryptocrystalline quartz, SiO₂; chalcedony variety colored by iron oxides

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; orange to reddish-orange, translucent to opaque, and typically waxy to dull luster. It has a microcrystalline quartz structure, no visible cleavage, conchoidal fracture, and specific gravity about 2.60–2.65.

Identified August 22, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, with iron producing the orange color; deposits commonly range from Cenozoic to older volcanic-hosted occurrences. The rounded appearance indicates polishing or natural abrasion.

Uses & applications

Used for beads, cabochons, carvings, seals, and inexpensive jewelry; also collected as a lapidary material.

Geological facts

Carnelian is a red-orange chalcedony; darker color generally reflects higher iron-oxide content. Similar orange glass, dyed agate, or resin can imitate it.

Field identification & locations

Field tests include glass scratching, a waxy texture, conchoidal fracture, and lack of cleavage; color may be uneven or banded. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.