Checkout the face in the Septarian Nodule Bookend Set from Utah
Utah Septarian Nodules (geode)
Utah Septarian Nodules are found 15 miles east of Zion National Park, Utah. They are formed in an ancient sea floor during the cretaceous period 50-70 million years ago. As they weathered out of the gray clay hills, at one time they could be picked up on the surface. Now bulldozers are required for their extraction, usually 20-30 ft. underground.
Some geodes are filled completely with calcite, while others are hollows showing calcite crystals.
The composition of the Septarian is as follows:
White or clear.......Barite
One half measures at 3 3/4 x 4 1/2 x 2 inches thick. 7 5/8 in length.