thoria

[thawr-ee-uh, thohr-] /ˈθɔr i ə, ˈθoʊr-/
noun, Chemistry
1.
a white, heavy, water-insoluble powder, ThO 2 , used chiefly in incandescent mantles, as the Welsbach gas mantle.
Also called thorium oxide, thorium dioxide.
Origin
1835-45; thori(um) + -a4
British Dictionary definitions for thoria

thoria

/ˈθɔːrɪə/
noun
1.
another name for thorium dioxide
Word Origin
C19: thorium + -a, on the model of magnesia