gemstone

Tumbled carnelian

Chalcedony (microcrystalline quartz), SiO₂; iron-colored variety

AI-generated identification · may be incorrect

Typically orange-red to reddish brown, translucent, with a waxy to vitreous luster and no visible crystal faces. Mohs hardness 6.5–7; conchoidal fracture, specific gravity about 2.60–2.65; polishing and rounded shape indicate tumbling.

Identified August 23, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron oxides producing the red-orange color; commonly associated with volcanic rocks and formed during the Cenozoic or earlier. The specimen is human-polished rather than naturally weathered.

Uses & applications

Used for beads, cabochons, carvings, pendants, and inexpensive decorative stones; historically used for seals and amulets. Common tumbled pieces have modest collector value.

Geological facts

Carnelian is a variety of chalcedony, closely related to sard; color may deepen with gentle heating. Strong translucency and evenly distributed color are typical of quality material.

Field identification & locations

Identify by its orange-red translucency, smooth waxy polish, hardness, and lack of cleavage; common sources include India, Brazil, Uruguay, Madagascar, and Botswana. Check for bubbles or flow texture, which may indicate glass imitation.