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Webster 1913 Edition
Thorium
Tho′ri-um
,Noun.
[NL. See
Thorite
.] (Chem.)
A metallic element found in certain rare minerals, as thorite, pyrochlore, monazite, etc., and isolated as an infusible gray metallic powder which burns in the air and forms thoria; – formerly called also
thorinum
. Symbol Th. Atomic weight 232.0.