The vast majority of beryllium extant today is the product of spallation of larger atomic nuclei as a result of collision with cosmic rays and is a relatively rare element in the universe. Within the cores of stars beryllium is depleted as it is fused and creates larger elements. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl (aquamarine, emerald) and chrysoberyl.