mineral

Chalcedony

Silicon Dioxide (SiO2)

Hardness: 6.5 to 7 on the Mohs scale. Color: White, gray, yellowish, or translucent. Luster: Waxy to vitreous. Crystal structure: Microcrystalline or cryptocrystalline quartz. Cleavage: None, exhibits conchoidal fracture. Specific gravity: 2.58 to 2.64.

Hardness: 6
Color: White, gray, yellowish, or translucent
Luster: Waxy to vitreous

Identified August 1, 2026More mineral →

Explore Chalcedony 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

Formed in low-temperature environments through the deposition of silica-rich solutions from groundwater or hydrothermal fluids filling cavities in rocks, often during the Cenozoic era or older geological periods.

Uses & applications

Used in ornamental carvings, gemstone jewelry, bead-making, and mineral specimen collecting.

Geological facts

Chalcedony is the parent mineral species for many well-known varieties such as agate, jasper, carnelian, and onyx. The specimen shown features small hollow cavities or vugs lined with tiny quartz microcrystals.

Field identification & locations

Can be identified by its waxy luster, conchoidal fracture, and hardness capable of scratching glass. Commonly found worldwide in volcanic rock cavities, river gravels, and sedimentary deposits. Collectors look for unique botryoidal or vuggy structures.