mineral

Chalcedony (Agate)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Translucent tan to creamy white with green mossy inclusions. Luster: Waxy to vitreous. Crystal structure: Trigonal (cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Translucent tan to creamy white with green mossy inclusions
Luster: Waxy to vitreous

Identified July 17, 2026More mineral →

Explore Chalcedony (Agate) 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 through the deposition of silica-rich groundwater in the cavities or vesicles of volcanic or sedimentary rocks. This specimen likely formed in an igneous host rock as indicated by the mossy chlorite or celadonite inclusions.

Uses & applications

Used primarily for lapidary work, jewelry making (cabochons), as pocket stones for collectors, and historically for making tools or seals due to its toughness.

Geological facts

Chalcedony is a cryptocrystalline form of quartz, meaning its crystals are too small to be seen with a normal microscope. When it exhibits banding or specific inclusions like this one, it is often classified as Agate or Moss Agate.

Field identification & locations

Identify in the field by its waxy texture, conchoidal (shell-like) fracture, and inability to be scratched by a steel knife. Common in riverbeds, desert washes, and near ancient volcanic activity.