Turritella Jasper
Silicon dioxide (SiO2) with fossil gastropod inclusions
A fossiliferous jasper packed with spiral snail shells, technically a silicified gastropod limestone from Wyoming.
- Mohs hardness
- 6.5-7
- Color
- Brown to dark grey-black with cream fossil snail shells
- Type
- sedimentary
Got a rock like this?
Identify any rock from a photo, free.
Overview
Turritella Jasper (more often called Turritella Agate) is a fossil-rich silica stone composed of the spiral shells of ancient freshwater snails embedded in a dark brown to black silicified matrix. Despite the name, the fossils are actually the gastropod Elimia tenera, not true Turritella (a marine genus), a long-standing misnomer in the trade.
The stone comes from the Green River Formation of Wyoming, USA, where it formed in ancient lake sediments roughly 50 million years ago. Polished slabs reveal cross-sections of countless coiled shells, making it both a gemstone and a fossil specimen.
It straddles categories: a silicified, fossiliferous sedimentary rock cut and sold as jasper or agate.
Formation & geology
Turritella Jasper formed in the freshwater lakes of the Eocene Green River Formation. Vast numbers of Elimia snail shells accumulated on the lakebed and were buried in fine sediment.
Over time, silica-rich groundwater permeated the shell-rich limey mud, replacing and cementing it into a dense, hard silica rock while preserving the shells in cross-section. The dark matrix comes from organic material and iron, and the stone is quarried from the Green River beds of southwestern Wyoming.
How to identify it
This stone is unmistakable: a dark brown to black body densely packed with cream or tan spiral snail-shell cross-sections. Hardness is 6.5-7, scratching glass; streak is white.
The visible fossils are the key identifier; no other common jasper shows such dense gastropod shells. It is often labeled "agate," but the matrix is generally opaque jasper. Distinguish from look-alike fossil coquina by the silicified hardness and glassy polish.
Uses & significance
Turritella Jasper is popular both as lapidary material, cut into cabochons, beads, and slabs, and as an affordable fossil specimen for collectors and educators. The fossil shells make it a favorite conversation piece.
Metaphysically it is marketed as a grounding stone connected to ancient earth energy and past lives. Its genuine appeal is the combination of durability, attractive polish, and visible 50-million-year-old fossils.
Frequently asked questions
Are the fossils in Turritella Jasper really Turritella?
No. They are freshwater snails of the genus Elimia; the name Turritella is a long-standing trade misnomer.
Where does Turritella Jasper come from?
The Green River Formation of southwestern Wyoming, USA, where it formed in Eocene lake sediments.
Is it a jasper or an agate?
It is usually opaque silicified fossil rock; it is sold as both jasper and agate, with 'agate' being the more common trade name.
How old are the fossils?
Roughly 50 million years old, from the Eocene epoch.
Turritella Jasper guides
In-depth guides for identifying, valuing, and understanding Turritella Jasper.
Turritella Jasper identified by the community
Real specimens identified with Rock Identifier.
