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4.5" Fluorescent Fossil Clam • Mercanaria permagna • Ruck's Pit • Fort Drum, Fl.

$ 15.33

Availability: 91 in stock
  • Condition: This specimen measures 4.25" in width and is embedded in a matrix that is 5.5" from end to end. It weighs 1 pound 4.6 oz. and is an excellent example of an invertebrate fossil in transition. You can see where the shell has dissolves and calcite has begun to replace the shell. Additionally, the coquina comprising the matrix is a wonderful example of that type of sedimentary rock.
  • Modified Item: Yes
  • Modification Description: Cleaned & Trimmed
  • Country/Region of Manufacture: United States

    Description

    Up for grabs is one fossil clam, Mercanaria permagna, collected from Ruck's Pit in Fort Drum, Florida.  It is found in the sediment layers of the Nashua Formation which is dated to the Plio-Pleistocene Age, roughly 1.8 to 2.2 million years ago.  These are educational grade fossils that serve as an excellent example of specimens that show "fossilization in action”,  Depending on where you look in the layers of Ruck’s Pit you can find examples of the progression of changes that happen when fossils are created including:
    a.  shells that are mostly original and nearly intact with some limestone mud inside,
    b.  shells that exhibit  both the original shell as well as parts of the same shell that was dissolved by acidic ground water and then replaced by calcite and
    c.  shells that are completely replaced with golden calcite crystals  (this kind of mineral replacement is the same process that also produces geodes, dinosaur bones and petrified wood).
    It is important to note that they DO NOT have an abundance of the gold calcite crystals that are considered to be the hallmark of the higher end, museum quality specimens.   They are, however, encased in the original limestone coquina sediments that preserved and protected them for almost 2 millions years and, when you turn out the lights, they fluoresce in UV light.  You will receive the same clam in matrix that is seen in the pictures which were shot outside in natural light.  You will also be the first owner of this Dennison of the Ancient Dinner Table since it was extracted from the walls of Ruck's Pit.  Thanks for the look, class dismissed.