This is a very nice, good quality Schafite Set of 4.  They  measure from 1 5/8″ to 2″. The Schafites have a natural, iridescent, pearl-like finish with great colors which is very difficult to capture in a photo.  This excellent fossil is from the Upper Cretaceous Fox Hills Formation in north central South Dakota.  These fossils make great gifts or work wonderful as an educational tool for school, scouts or clubs.