sedimentary
Turritella Agate (Fossiliferous Chert)
Silicified Elimia tenera (Fossiliferous Chalcedony)
Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, cream, and black; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline (Cryptocrystalline); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.60-2.65.
- Hardness
- 6
- Color
- Brown, tan, cream, and black
- Luster
- Waxy to vitreous
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Brown, tan, cream, and black; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline (Cryptocrystalline); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.60-2.65.
Formation & geological history
Formed during the Eocene Epoch (approx. 50 million years ago) in freshwater lakes. This is a silicified fossiliferous stone where the spiral shells of freshwater snails (Elimia tenera) were replaced by chalcedony/agate.
Uses & applications
Used primarily for lapidary work, jewelry (cabochons), interior decoration items (like the bowl shown), and as collectible fossil specimens.
Geological facts
Despite its common name 'Turritella Agate,' the fossils are actually freshwater snail shells of the genus Elimia, not the marine snail Turritella. It is the official state fossil of Wyoming.
Field identification & locations
Identify by the distinctive spiral-shaped snail shells embedded in a dark or light silicate matrix. It is famously found in the Green River Formation in Wyoming, USA. Collectors look for high contrast between the fossils and the surrounding stone.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite
sedimentary