4.2" Calcite Crystal Filled Fossil Clam - Fluoresces Under UV

This is a large fossil clam of the species Mercenaria permagna from the the famous Ruck's Pit quarry in Florida. It's over 4.2 inches wide and the interior is filled with large, golden-yellow calcite crystals, almost like a fossil geode. It's early Pleistocene in age, or somewhere around 2 million years. The calcite crystals fluoresce beautifully under UV light.
Ruck's Pit was a small cement quarry, that for several years in the early 2000's produced some amazing crystal lined fossils. The quarry has been shut down and filled in with water for several years, so these fossils are no longer being found. Because of this it's difficult to acquire these remarkable crystal filled fossil shells, particularly ones of high quality such as this one.

A geological paper on they unique geology and fossil occurrences in Ruck's Pit can be found here.