Thorianite [SEP] named after
Thorianite
Thorianite is a rare thorium oxide mineral, ThO. It was originally described by Ananda Coomaraswamy in 1904 as uraninite, but recognized as a new species by Wyndham R. Dunstan. It was so named on account of its high percentage of thorium; it also contains the oxides of uranium, lanthanum, cerium, praseodymium and neodymium. Helium is present, and the mineral is slightly less radioactive than pitchblende, but is harder to shield due to its high energy gamma rays. It is common in the alluvial gem-gravels of
contained a new element (#71), which he named "cassiopeium". Urbain proved this simultaneously, but his samples were very impure and only contained trace quantities of the new element. Despite this, his chosen name "lutetium" was adopted.
In 1908, Ogawa found element 75 in thorianite but assigned it as element 43 instead of 75 and named it "nipponium". In 1925 Walter Noddack, Ida Eva Tacke and Otto Berg announced its separation from gadolinite and gave it the present name, "rhenium