P. T. (Per Teodor) Cleve

Born in Stockholm in 1840, Per Teodor Cleve studied at Uppsala University and went on to build a long academic career there. He became known as a chemist of unusual range, with interests that stretched beyond the laboratory into mineralogy, biology, and the study of the sea.

Cleve is most often remembered for his work on the rare earth elements, especially for discovering holmium and thulium. He also helped show that the substance once called didymium was not a single element, but something more complex than scientists had first believed.

Over time, his research widened into oceanography, adding yet another field to an already varied career. He died in Uppsala in 1905, leaving behind the picture of a scholar whose scientific life was both broad and deeply inquisitive.