Rock Identifier
Tumbled amber-colored chalcedony (likely carnelian) (Chalcedony, microcrystalline quartz (SiO₂); orange-red variety called carnelian) — mineral
mineral

Tumbled amber-colored chalcedony (likely carnelian)

Chalcedony, microcrystalline quartz (SiO₂); orange-red variety called carnelian

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange-brown color with waxy to vitreous luster and no visible cleavage. It is cryptocrystalline quartz, commonly occurring as rounded pebbles or nodules.

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Physical properties

Hardness 6.5–7 Mohs; translucent orange-brown color with waxy to vitreous luster and no visible cleavage. It is cryptocrystalline quartz, commonly occurring as rounded pebbles or nodules.

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, precipitating microscopic quartz fibers; iron impurities create the orange color. Deposits range from Paleozoic to Cenozoic in age and occur in volcanic and sedimentary terrains.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and inexpensive jewelry; durable polished pieces are popular lapidary material.

Geological facts

Carnelian is a traditional gemstone associated with ancient Egyptian, Roman, and Mesopotamian jewelry. Color may deepen after heating or prolonged sunlight exposure.

Field identification & locations

Identify it by its orange translucency, smooth waxy surface, conchoidal fracture, and hardness sufficient to scratch ordinary glass; it should not show bubbly glass texture. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.