The mineral cleveite is named for Cleve. Yttrogummite is a variant of cleveite also found in Norway. Additionally, Cleve and Abraham Langlet discovered helium in the mineral cleveite in 1895. Cleve and Abraham Langlet succeeded in isolating helium from cleveite at about the same time. Cleveite is an impure radioactive variety of uraninite containing uranium, found in Norway.