A rare element of atomic number 67 said to be contained in gadolinite. Chemical symbol Ho. Atomic weight 164.93. Valence +3. It was detected by spectral absorption bands in 1878 by the
Delafontaine and
Soret, who called it "Element X". Later the Swedish chemist
Cleve independently discovered it in erbia, and named it after his native city Stockholm. The first preparation of pure Holmia, the yellow oxide, was not made until 1911. [
1913 Webster]