mineral

Blue chalcedony (likely dyed or coated)

Chalcedony, microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Typically hardness 6.5–7, waxy to vitreous luster, translucent blue-gray color, and no visible cleavage; it is cryptocrystalline quartz with conchoidal fracture. The unusually vivid blue surface and brown patches suggest artificial dyeing/coating or included matrix.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich groundwater deposits microscopic quartz fibers in cavities and fractures, commonly in volcanic rocks. Formation ages vary widely, from relatively young deposits to ancient volcanic sequences.

Uses & applications

Used for cabochons, carvings, beads, and decorative objects; attractive natural blue chalcedony can be collectible. Dyed specimens generally have modest value.

Geological facts

Blue chalcedony is naturally uncommon, while dyed gray chalcedony is widespread in the mineral trade. A cotton swab moistened with acetone may lift dye from surface cracks, though this test can damage coatings.

Field identification & locations

Common sources include Turkey, Namibia, Indonesia, Brazil, and the United States. Field clues are waxy luster, translucency at thin edges, hardness sufficient to scratch glass, and conchoidal fracture; acid will not fizz.