mineral

Tumbled white chalcedony (likely milky quartz)

Chalcedony, microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; pale translucent white to bluish-white, vitreous-to-waxy luster, cryptocrystalline structure, and no visible cleavage. The rounded, glossy surfaces indicate tumbling and polishing.

Identified August 27, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, depositing microcrystalline quartz; specimens may range from young cavity fillings to Paleozoic and younger volcanic-hosted deposits.

Uses & applications

Used for inexpensive cabochons, beads, carvings, tumbled stones, and decorative objects; less commonly for industrial silica. These small polished pieces have modest collector value.

Geological facts

Milky appearance comes from microscopic inclusions, pores, or fluid. Some similar-looking beads are man-made glass or resin, so visual identification alone is not definitive.

Field identification & locations

Common sources include Brazil, Madagascar, India, Uruguay, and the western United States. Chalcedony typically scratches glass, shows no fizz in dilute acid, and feels harder and cooler than plastic; a gemological test can distinguish it from glass.