mineral
Tumbled orange chalcedony
Chalcedony (microcrystalline quartz, SiO₂), likely orange carnelian
AI-generated identification · may be incorrectTypically hardness 6.5–7 Mohs, translucent orange to honey-brown, with a waxy to vitreous luster and no visible cleavage; cryptocrystalline quartz has a trigonal structure. The smooth rounded form indicates tumbling or natural abrasion.
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Physical properties
Typically hardness 6.5–7 Mohs, translucent orange to honey-brown, with a waxy to vitreous luster and no visible cleavage; cryptocrystalline quartz has a trigonal structure. The smooth rounded form indicates tumbling or natural abrasion.
Formation & geological history
Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, precipitating as microcrystalline quartz; orange color commonly results from iron oxides. Chalcedony occurs from many geological ages, especially in volcanic terrains.
Uses & applications
Used for beads, carvings, cabochons, ornaments, and lapidary specimens; common tumbled pieces generally have modest value.
Geological facts
Carnelian is the orange-red variety of chalcedony, though color boundaries with orange chalcedony are informal. It may be dyed or heat-treated in commercial material.
Field identification & locations
Identify by its glassy/waxy appearance, lack of cleavage, hardness, and inability to scratch with a steel nail easily; common sources include India, Brazil, Uruguay, Madagascar, and the United States.
