mineral

Chalcedony

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale. Color: Brown, grey, white, or translucent. Luster: Waxy to vitreous. Crystal structure: Microcrystalline quartz (cryptocrystalline), trigonal system. Cleavage: None, exhibits conchoidal fracture. Specific gravity: 2.58-2.62.

Hardness: 6
Color: Brown, grey, white, or translucent
Luster: Waxy to vitreous

Identified August 3, 2026More mineral →

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Physical properties

Formation & geological history

Forms in low-temperature aqueous environments, often filling cavities, vesicles, or fractures in volcanic and sedimentary rocks through the precipitation of silica-rich fluids.

Uses & applications

Used in ornamental carvings, gemstone cabochons, jewelry, and lapidary arts.

Geological facts

Chalcedony has been used since ancient times for making intricate seals, signet rings, and decorative objects. It serves as the parent material for many other gemstone varieties like agate, jasper, and onyx.

Field identification & locations

Identified by its waxy luster, conchoidal fracture, and microcrystalline structure. Found worldwide, particularly in volcanic regions and river gravels. Popular among rockhounds for tumbling and cabochon making.