gemstone

Blue-gray chalcedony cabochon

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

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; waxy to vitreous luster, pale blue-gray color, cryptocrystalline quartz structure, no visible cleavage, and specific gravity about 2.58–2.64. The smooth oval shape indicates a polished cabochon.

Identified September 10, 2026More gemstone →

Explore Blue-gray chalcedony cabochon in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms when silica-rich groundwater deposits microscopic quartz fibers in cavities and fractures, commonly in volcanic rocks. Formation ages range from ancient volcanic episodes to relatively young hydrothermal deposits.

Uses & applications

Used for cabochon jewelry, beads, carvings, and ornamental objects; generally affordable unless strongly colored, translucent, or displaying attractive banding.

Geological facts

Blue chalcedony gets its color from fine mineral inclusions or microscopic scattering; some commercial material is dyed. It may be confused with blue aventurine, glass, or blue-gray moonstone.

Field identification & locations

Common sources include Turkey, Namibia, Madagascar, Brazil, India, and the United States. Field clues are its cool feel, waxy luster, hardness sufficient to scratch glass, and lack of bubbles or flow texture; confirmation requires gemological testing.