Clam with calcite replacement

Name Clam with calcite replacement
Scientific Name Mercenaria Permagna
Category Fossils
Origion Okeechobee, FL

Historic Background

The Mercenaria is a genus of bivalve mollusks in the family Veneridae. The species were formerly placed in the related genus Venus.

This piece of fossil is a type of clam called Mercenaria Permagna. It lived in the Pliocene – Pleistocene era – about 3 million years ago. The matrix is a mixture of fossil shells in fossilized kelp, which is largely composed of titanium. Fluoresces both long and short waves. Golden color due to iron atom in forming process of Rucks area 2 to 2.5 million years ago.


A small find of these clam shell was discovered in 2002 during an excavation for a civil engineering project. A fascinating specimen formed when “gemmy” calcite crystals grew in the natural pockets inside the shell pocket. The crystals were often used in jewels because of its beautiful shape.

As of August 2006, digging in the Rucks Pit were no longer be permitted.

Physical Description:

The specimen is about 5 inches by 3.25 inches. It contains one large and two small clams within the titanium containing matrix. The two small clams contain small crystals. One of them is near complete. The large claim contains exceptional calcified matrix. Its pocket roof contains large dog-tooth calcite crystals displays on its natural rooting. The larger ones are about 0.375 inches long. The bottom of the pocket contains a bed of smaller calcite crystals with a few groups of larger ones sprouting out like flowers. A thin layer of titanium is also visible within the crystals. It weights about 14.5 oz.