sedimentary
Turritella Agate (Calligrapher Stone)
Silicified Elimia tenera (Chalcedony/Quartz)
Hardness: 6.5-7 (Mohs). Color: Dark brown to black matrix with yellowish-tan spiral snail fossils. Luster: Vitreous to waxy when polished. Structure: Cryptocrystalline. Cleavage: None (Conchoidal fracture). Specific gravity: 2.60-2.65.
- Hardness
- 6
- Luster
- Vitreous to waxy when polished
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Physical properties
Hardness: 6.5-7 (Mohs). Color: Dark brown to black matrix with yellowish-tan spiral snail fossils. Luster: Vitreous to waxy when polished. Structure: 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 the Green River Formation. It is created when freshwater snail shells (Elimia tenera) are replaced by silica (chalcedony) in a sedimentary environment.
Uses & applications
Primarily used for lapidary work, jewelry (cabochons), interior decoration, and as a popular 'healing' or collecting stone in various metaphysical communities.
Geological facts
Despite its trade name 'Turritella,' the fossils are actually of the freshwater genus Elimia, not the saltwater genus Turritella. This specific specimen is carved into an 'obelisk' or 'tower' shape.
Field identification & locations
Identify by the distinctive spiral snail shell patterns embedded in a dark siliceous matrix. It is most famously found in the Green River Formation of Wyoming, USA. Collectors should look for dense fossil concentrations.
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