Thorite ThSiO

About four years later in 1819, the Reverend Hans Morten Thrane Esmark (1801— 1882), an amateur mineralogist, found a black mineral in Norway and gave a sample of it to his father, a geology professor, for analysis. Unable to identify it, Professor Jens Esmark sent the sample for chemical analysis to Berzelius, who found that it contained 60% of a new type of earth oxide not recognized before. It was identified as the mineral thorite (ThSiO ). Berzelius reported his discovery in an 1829 publication and retained the name thorium, in honor of Thor, the Norse god of war. Berzelius is thus credited with thorium s discovery. 

Most important mineral Thorite ThSiO (Figure M24) and thorianite ThOj. 

Monazite is recovered mainly for its content of rare earth metals, and thorium has to be separated. This has led to an overproduction of thorium oxide. The excess is stored for potential use or disposed of as a radioactive waste. Most producers of rare earths have however switched to thorium-free raw materials due to the problems (and costs) of dealing with the radioactivity. This may change the situation for thorium supply. Other thorium minerals, besides monazite, are thorite ThSiO (Figure M24) and thorianite ThO. ... 

M24 Thorite ThSiO, from Evje in Norway. Tetragonal crystals, partially destroyed by radioactive decay. 

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