sedimentary
Turritella (Gastropod Fossil)
Turritella (Genus of gastropods), CaCO3 (Calcium Carbonate or Silicified Agate)
Hardness: 3-4 (if calcite) or 6.5-7 (if silicified); Color: Cream, tan, or grey; Luster: Dull to vitreous; Structure: High-spired conical shell (turriform); Cleavage: None/Conchoidal.
- Hardness
- 3-4 (if calcite) or 6
- Color
- Cream, tan, or grey
- Luster
- Dull to vitreous
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Physical properties
Hardness: 3-4 (if calcite) or 6.5-7 (if silicified); Color: Cream, tan, or grey; Luster: Dull to vitreous; Structure: High-spired conical shell (turriform); Cleavage: None/Conchoidal.
Formation & geological history
Formed through the accumulation of marine snail shells in sedimentary layers (limestone or sandstone), often silicified over millions of years. Most common specimens range from the Cretaceous to the Eocene period (approx. 50-100 million years old).
Uses & applications
Used primarily for fossil collecting, educational teaching sets, and in decorative lapidary arts (e.g., jewelry or bookends when found in 'Turritella Agate' blocks).
Geological facts
Despite being called 'Turritella Agate' in the trade, the famous Wyoming specimens are actually an extinct freshwater snail called Elimia tenera, though the name Turritella is still widely used in geological circles.
Field identification & locations
Identify in the field by the distinct spiral screw-like shape and visible whorls. Often found in fossiliferous limestone beds or eroded out of sedimentary cliffs near ancient shorelines.
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