These Septarian Egg's  are approximately 49 x 57 mm; thickness is approximately 45 mm, weight is approximately 159 grams. These dimensions are very general. There are three eggs each one does have a different set of dimensions. We are doing random pull on this unless we are contacted for a specific one in the photo(s). 
 
Septarian is also known as Dragon Stone. Septarian nodules were formed out of Aragonite, Barite Calcite and Limestone some 70 million years ago. Hardness is 3 and they are found in Utah, Madagascar, and Marocco. The Calcite veins do tend to UV light.