There has been some controversy surrounding the discovery of hafnium and the extent to which Coster and Hevesy were guided by Bohr's prediction that hafnium would be a transition metal rather than a rare earth element.
Terdapat beberapa kontroversi seputar penemuan hafnium dan pendapat Coster dan Hevesy yang mengacu pada prediksi Bohr bahwa hafnium adalah logam transisi dan bukan unsur tanah jarang.