Turritella Agate Value Guide

Turritella Agate is a unique fossiliferous chalcedony prized for its striking patterns of spiral Elimia tenera snail shells suspended in a dark matrix. Formed over 46 million years ago in the Eocene epoch, this material serves as a prehistoric snapshot of the ancient Lake Gosiute ecosystem.

What affects the value of Turritella Agate?

• The clarity and contrast between the fossilized shells and the surrounding dark agate matrix significantly impact market price.
• Specimen size and the quality of the lapidary work, such as cabochons or polished slabs, dictate the $15 to $25 value range.
• The structural integrity of the fossils, specifically whether the delicate spiral tips of the shells are intact and visible.
• The presence of unique druzy pockets or secondary mineralization within the shell cavities can increase collector interest.

How to Identify Turritella Agate?

• Look for distinct white or cream-colored spiral shell inclusions set against a dark brown or black translucent chalcedony background.
• Verify the fossil type as Elimia tenera, a freshwater snail, rather than the marine Turritella genus for which it was misnamed.
• Check for a high-gloss vitreous luster when polished, which is characteristic of high-silica agate from the Green River Formation.
• Examine the density of the fossils; authentic specimens typically show a high concentration of shells packed within the silica-rich sediment.

History of Turritella Agate

Named incorrectly after the Turritella sea snail, this material actually contains the freshwater snail Elimia tenera. It formed in Lake Gosiute during the Eocene epoch, where millions of snails were preserved in silica-rich sediment, eventually turning into agate. It is primarily found in the Green River Formation of Wyoming.