Large (3 Inch) Pterocephalia Nodule

This is a large Pterocephalia norfordi trilobite preserved inside a thick calcite nodule. These calcite nodules if they have been sufficiently weather and have gone through enough freeze/thaw cycles will split open naturally but this one hasn't. While Pterocephalia is known to achieve truly massive sizes close of around 8 inches they only average about an inch in length and this one is quite large.

Access to the sites where these trilobites come from is fairly limited because they now lie on mineral claims. This trilobite is part of a group I acquired in a trade with one of the claim holders.