mineral

Blue chalcedony (likely dyed or polished)

Microcrystalline quartz, SiO₂ (chalcedony variety)

AI-generated identification · may be incorrect

Typically hardness 6.5–7 Mohs, translucent blue to gray-blue, waxy to vitreous luster, and no visible cleavage; cryptocrystalline quartz has a trigonal structure. The rounded, glossy surface indicates tumbling or polishing.

Identified September 3, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, commonly in volcanic rocks; coloration may be natural or enhanced by dye. Deposits range from Paleozoic to Cenozoic, depending on locality.

Uses & applications

Used for cabochons, beads, carvings, and ornamental objects; common polished pieces have modest value.

Geological facts

Blue chalcedony’s color can result from microscopic inclusions or defects, while vivid, uniform blue often suggests treatment. It may resemble blue calcite, glass, or dyed quartzite.

Field identification & locations

Common sources include Turkey, Namibia, Madagascar, Indonesia, Brazil, and the western United States. Quartz hardness, lack of cleavage, waxy luster, and conchoidal fracture help distinguish it; avoid scratching finished surfaces.