sedimentary

Silicified Gastropod Fossil (Agatized Fossil)

Gastropoda (Class) preserved in Chalcedony/Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs); Color: Tan, beige, and opaque white; Luster: Waxy to vitreous; Structure: Helical/spiral coil; Cleavage: None (conchoidal fracture)

Hardness: 6
Color: Tan, beige, and opaque white
Luster: Waxy to vitreous

Identified June 23, 2026More sedimentary →

Explore Silicified Gastropod Fossil (Agatized Fossil) 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 (Mohs); Color: Tan, beige, and opaque white; Luster: Waxy to vitreous; Structure: Helical/spiral coil; Cleavage: None (conchoidal fracture)

Formation & geological history

Formed via permineralization where silica-rich groundwater replaced the organic shell structure of a prehistoric snail within sedimentary layers like limestone or shale.

Uses & applications

Educational specimens, hobbyist collecting, jewelry (when polished), and lapidary art.

Geological facts

Gastropod fossils date back to the Cambrian period. This specific specimen shows 'silicification,' which turns once-brittle shell into durable quartz-based stone.

Field identification & locations

Identify by the distinct spiral 'screw' shape and ridges. Commonly found in eroded creek beds or limestone quarries. Test hardness against steel; it will scratch glass.