Cleveite

Cleveite is an impure radioactive variety of uraninite containing uranium, found in Norway.

[2] It was named after Swedish chemist Per Teodor Cleve.

Cleveite was the first known terrestrial source of helium, which is created over time by alpha decay of the uranium and accumulates trapped (occluded) within the mineral.

[3] Cleve and Abraham Langlet succeeded in isolating helium from cleveite at about the same time.

Yttrogummite is a variant of cleveite also found in Norway.

The cleveite sample from which Ramsay first purified helium, in the collection of University College London [ 1 ]