mineral

Blue chalcedony or dyed agate (tentative)

Microcrystalline quartz, SiO₂; color may be enhanced by dye or coating

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent blue with brown/gray patches and a waxy to glassy luster. It lacks visible cleavage and commonly has cryptocrystalline quartz structure; the irregular shape suggests a tumbled or polished specimen.

Identified August 26, 2026More mineral →

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Physical properties

Formation & geological history

Chalcedony forms when silica-rich groundwater fills cavities and fractures, precipitating as microscopic quartz fibers, commonly in volcanic rocks. Its exact geological age and whether the vivid blue color is natural cannot be determined from the image.

Uses & applications

Used for cabochons, carvings, beads, and decorative specimens; lower-grade pieces are inexpensive lapidary material.

Geological facts

Natural blue chalcedony is usually pale to medium blue; intensely saturated blue stones are often dyed, coated, or marketed as “blue agate.”

Field identification & locations

Common sources include Brazil, Uruguay, India, Madagascar, Turkey, and the western United States. Check for color concentration in cracks or around edges, which can indicate dye; a quartz hardness test should scratch glass but may damage the specimen.