mineral

Tumbled carnelian/chalcedony

Chalcedony (microcrystalline quartz), SiO₂; reddish color from iron oxides

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent gray-brown to red-orange, with a waxy to vitreous luster and no visible cleavage. It has a cryptocrystalline quartz structure and conchoidal fracture; the smooth surface indicates tumbling or water wear.

Identified August 9, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, with iron staining producing red tones. Deposits commonly formed during the Cenozoic and older volcanic episodes.

Uses & applications

Used as an ornamental stone, beads, cabochons, carvings, and lapidary material; durable enough for minor decorative and historical tool uses.

Geological facts

Carnelian is the orange-red variety of chalcedony, while gray or brown translucent portions may be ordinary chalcedony. Heating can intensify its red color by oxidizing iron.

Field identification & locations

Identify by its waxy appearance, translucency, quartz hardness, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include India, Brazil, Uruguay, Madagascar, and the western United States.