mineral
Tumbled blue chalcedony (likely blue quartz)
Chalcedony, cryptocrystalline SiO₂; possibly chrysoprase or dyed quartz
AI-generated identification · may be incorrectMohs hardness 6.5–7; pale blue, opaque to translucent, waxy-to-glassy luster, and no visible cleavage. The rounded shape indicates tumbling and the surface appears smoothly polished.
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Physical properties
Mohs hardness 6.5–7; pale blue, opaque to translucent, waxy-to-glassy luster, and no visible cleavage. The rounded shape indicates tumbling and the surface appears smoothly polished.
Formation & geological history
Chalcedony forms when silica-rich groundwater fills cavities and fractures, commonly in volcanic rocks; deposits range from Paleozoic to recent. Blue coloration may result from microscopic inclusions or artificial dyeing.
Uses & applications
Used as a lapidary stone for cabochons, beads, carvings, and ornamental objects; small tumbled pieces are commonly sold as décor or beginner specimens.
Geological facts
Blue chalcedony is rarer and generally more valuable than ordinary gray or white chalcedony. A strong, uniform blue color can indicate treatment rather than natural color.
Field identification & locations
Common sources include Turkey, Namibia, Indonesia, Madagascar, and the western United States. Identify it by its fine-grained waxy appearance, lack of cleavage, and resistance to scratching by steel; exact identification requires testing.
