sedimentary

Eye Agate

Chalcedony (Silicon Dioxide, SiO2)

Hardness: 6.5-7 on Mohs scale. Color: Brown matrix with white/clear concentric circular 'eyes'. Luster: Waxy to vitreous. Structure: Cryptocrystalline. Cleavage: None. Specific Gravity: 2.58-2.64.

Hardness: 6
Color: Brown matrix with white/clear concentric circular 'eyes'
Luster: Waxy to vitreous

Identified July 20, 2026More sedimentary →

Explore Eye Agate in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 6.5-7 on Mohs scale. Color: Brown matrix with white/clear concentric circular 'eyes'. Luster: Waxy to vitreous. Structure: Cryptocrystalline. Cleavage: None. Specific Gravity: 2.58-2.64.

Formation & geological history

Formed in volcanic or sedimentary rock cavities where silica-rich groundwater deposited layers of chalcedony over time. The 'eye' patterns are formed by point-source crystallization during the deposition process.

Uses & applications

Commonly used in jewelry, as tumbled pocket stones, in lapidary work, and as collectibles for metaphysical or aesthetic purposes.

Geological facts

Agates with 'eye' patterns have been historically used as amulets to ward off the 'evil eye'. Many eye agates, like the Lake Superior Agate, date back over a billion years to the Proterozoic era.

Field identification & locations

Identify by the distinct bullseye or concentric circular patterns on the surface. Commonly found in riverbeds, lakeshores (like the Great Lakes), and gravel pits. Collectors look for high contrast and centered eyes.