sedimentary

Turritella Agate

Silicified Elimia tenera Fossil (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, black, and white; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None; Specific gravity: 2.58-2.64

Hardness: 6
Color: Brown, tan, black, and white
Luster: Waxy to vitreous

Identified March 30, 2026More sedimentary →

Explore Turritella 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 (Mohs scale); Color: Brown, tan, black, and white; Luster: Waxy to vitreous; Crystal structure: Cryptocrystalline; Cleavage: None; Specific gravity: 2.58-2.64

Formation & geological history

Formed through the silicification of freshwater snail shells (Elimia tenera) during the Eocene epoch (approx. 50 million years ago) in lacustrine (lake) environments, specifically within the Green River Formation.

Uses & applications

Primarily used in lapidary work for making cabochons, beads, and jewelry; also popular as a decorative display stone or for metaphysical collecting.

Geological facts

Despite its common name, it does not actually contain 'Turritella' marine snails; it contains 'Elimia' freshwater snails. It is one of the most famous examples of fossiliferous chalcedony in the world.

Field identification & locations

Identify by looking for distinct spiral-shaped snail shell fossils embedded in a darker chalcedony matrix. It is found almost exclusively in the Green River Formation in Wyoming, USA. Collectors should look for high contrast between the fossils and the surrounding rock.