mineral

Chalcedony on Matrix

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Translucent honey-yellow to amber with grey host rock. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline (hexagonal/trigonal). Cleavage: None, conchoidal fracture.

Hardness: 6
Color: Translucent honey-yellow to amber with grey host rock
Luster: Waxy to vitreous

Identified May 21, 2026More mineral →

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Physical properties

Formation & geological history

Formed from the deposition of microcrystalline silica in volcanic or sedimentary cavities at relatively low temperatures. Often found in hydrothermal veins or as a secondary mineral in basalt vesicles.

Uses & applications

Used primarily for lapidary work, semi-precious jewelry, and as decorative cabinet specimens for mineral collectors.

Geological facts

Chalcedony was one of the first materials used by early humans for tools because of its hardness and the sharp edges it creates when fractured. It is a fibrous variety of quartz.

Field identification & locations

Identify in the field by its waxy appearance, translucency, and inability to be scratched by a steel knife. Common in desert environments and areas with ancient volcanic activity.