gemstone

Blue chalcedony cabochon

Microcrystalline quartz (SiO₂), chalcedony variety

AI-generated identification · may be incorrect

Translucent blue, polished domed cabochon with a waxy-to-vitreous luster. Mohs hardness 6.5–7; cryptocrystalline quartz, with no visible cleavage and conchoidal fracture. The photograph alone cannot confirm whether its color is natural or treated.

Identified September 26, 2026More gemstone →

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Physical properties

Formation & geological history

Silica-rich fluids deposit microscopic quartz fibers in cavities and fractures, commonly in volcanic rocks; chalcedony forms across many geological ages. Blue color may result from trace impurities or treatment.

Uses & applications

Cut into cabochons for jewelry and used for carvings and ornamental objects.

Geological facts

Chalcedony is a broad family that includes agate, carnelian, and chrysoprase; blue material is sometimes dyed to intensify its color.

Field identification & locations

Look for a smooth, uniform, translucent body, waxy luster, and lack of visible crystal faces; common sources include Brazil, India, Madagascar, and the United States. This small, polished piece appears to be a gemstone rather than a whole rock.