mineral
Tumbled orange chalcedony (likely carnelian)
Cryptocrystalline quartz, SiO₂; orange variety commonly called carnelian
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; translucent honey-orange color, waxy to vitreous luster, and no visible crystal faces or cleavage. The rounded shape indicates mechanical tumbling and polishing; color may reflect iron impurities or enhancement.
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Physical properties
Hardness 6.5–7 Mohs; translucent honey-orange color, waxy to vitreous luster, and no visible crystal faces or cleavage. The rounded shape indicates mechanical tumbling and polishing; color may reflect iron impurities or enhancement.
Formation & geological history
Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, with iron producing orange-red coloration; deposits range from relatively young to Cenozoic and older. It is commonly associated with basaltic cavities and weathered silica deposits.
Uses & applications
Used for cabochons, beads, carvings, and inexpensive jewelry; tumbled pieces are popular decorative and collecting specimens.
Geological facts
Carnelian is a variety of chalcedony, itself a microcrystalline form of quartz. Stronger red-orange color and translucency generally increase desirability.
Field identification & locations
Identify it by its uniform waxy appearance, hardness, translucency, 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 United States.
