mineral

Tumbled blue chalcedony

Chalcedony, microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; pale blue, translucent, waxy-to-vitreous luster, cryptocrystalline structure, and no visible cleavage. The smooth rounded surface is from tumbling and polishing.

Identified August 19, 2026More mineral →

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Physical properties

Mohs hardness 6.5–7; pale blue, translucent, waxy-to-vitreous luster, cryptocrystalline structure, and no visible cleavage. The smooth rounded surface is from tumbling and polishing.

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, depositing microscopic quartz fibers, commonly in volcanic rocks. Deposits range from Precambrian to recent; the image alone cannot establish age or locality.

Uses & applications

Used for cabochons, beads, carvings, ornamental objects, and inexpensive jewelry. It is durable but may scratch softer materials and can fracture under strong impact.

Geological facts

Blue color may result from inclusions, scattering, or minor impurities; some commercial blue chalcedony is dyed or treated. Chalcedony is a variety of quartz that includes agate, jasper, and onyx varieties.

Field identification & locations

Identify by its even blue translucency, waxy appearance, smooth conchoidal fracture, and hardness sufficient to scratch glass. Common sources include Brazil, Namibia, Turkey, Madagascar, India, and the United States; laboratory testing is needed to distinguish it from glass or dyed quartz.