mineral

Tumbled carnelian/chalcedony

Orange chalcedony (microcrystalline quartz), SiO₂; possibly iron-stained agate

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, waxy to vitreous luster, orange to reddish-orange color, translucent edges, and no visible cleavage. The specimen appears smoothly tumbled, with cloudy white-gray quartz patches and iron-oxide coloration.

Identified September 7, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, later developing cryptocrystalline quartz; orange color comes mainly from hematite or limonite. Chalcedony deposits occur from Precambrian to recent ages in volcanic and sedimentary environments.

Uses & applications

Used for beads, cabochons, carvings, and ornamental objects; durable pieces are popular inexpensive gemstones and lapidary material.

Geological facts

Carnelian is the orange-red variety of chalcedony, while sard is the darker brown-red variety; boundaries between them are gradual. Heating can intensify its orange-red color.

Field identification & locations

Identify by its hardness, smooth waxy appearance, translucency, and lack of cleavage; it should resist scratching by a steel knife but scratch glass. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.