sedimentary

Turritella Agate

Chalcedony quartz with fossilized gastropods

Hardness of 6.5 to 7 on the Mohs scale, featuring distinct spiral fossil shells in a brown or black matrix with vitreous luster.

Identified October 28, 2026More sedimentary →

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Physical properties

Hardness of 6.5 to 7 on the Mohs scale, featuring distinct spiral fossil shells in a brown or black matrix with vitreous luster.

Formed in ancient freshwater lakes and lagoons through the silicification of fossilized Turritella snail shells over millions of years.

Used primarily in lapidary arts, cabochons, and gemstone jewelry or as collector specimens.

Despite its common trade name, the fossil shells are actually from the freshwater snail Elimia tenera rather than marine Turritella.

Easily identified by its matrix packed with contrasting small white spiral gastropods, found prominently in the Green River Formation of Wyoming.

Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion

Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Sandstone or Siltstone

Arenite (if sandstone)

Sandstone

Arenite

Shale

Shale (clastic sedimentary rock)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)