MINERAL OF THE MONTH: March 2010 – Fossilized Dinosaur Bone

This month’s featured mineral is fossilized dinosaur bone. For the new agate book, Tom Shearer borrowed samples of fossilized bone from Mark Anderson (www.differentseasonsjewelry.com). The specimens pictured below come from Utah. Although they certainly have agate pockets, technically the fossilization process is different than the agatization process. Therefore, these specimens are classified as fossilized dinosaur bones that have agate pockets.

You might wonder how these bones become fossilized in the first place. The process happened as follows:

  1. After their death, dinosaurs became buried in mud or sand.
  2. The softer tissues decayed and rotted. However, the harder parts like bones and teeth did not rot and became encased in the sediment.
  3. In time mineral-rich water seeped into the bone. The process of fossilization occurred in two different ways. Either the original organic material was replaced with other minerals (permineralization), or tiny spaces in the bone filled in with minerals (recrystallization). In the case of the fossil photographs included below, agate filled in some of the spaces.
  4. This process causes the bone to turn into a fossil. The fossil has the same shape as the original bone, but chemically has been converted to rock!


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