sedimentary
Turritella Agate
Silicified Elimia tenera Fossil (SiO2)
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
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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.
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