mineral

Tumbled blue chalcedony (probable)

Chalcedony, microcrystalline quartz (SiO₂), possibly blue quartz or dyed chalcedony

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; pale blue-gray, with a dull to waxy luster and rounded tumbled form. Chalcedony has cryptocrystalline quartz structure, no obvious cleavage, and specific gravity near 2.6; the brown patch may be iron-oxide staining or matrix.

Identified August 26, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater deposits microscopic quartz fibers in volcanic cavities and fractures, commonly during Cenozoic and older geological episodes. Tumbled shaping is human processing rather than natural formation.

Uses & applications

Used for cabochons, beads, carvings, ornamental objects, and lapidary practice; durable enough for some jewelry. Common polished pieces generally have modest value.

Geological facts

Blue chalcedony’s color comes from fine inclusions or light-scattering effects; vivid, uniform blue material is sometimes dyed. The photograph alone cannot confirm natural color or exact variety.

Field identification & locations

Common sources include Brazil, Uruguay, Namibia, Turkey, and the United States. Identify by its waxy appearance, lack of visible grains, and hardness; glassy fractures and uniform dye concentration can indicate imitation or treatment.