Th - Thorium
(Thor, Scandinavian god of war) Discovered by Berzelius in 1828. Much of the internalheat the earth produces has been attributed to thorium and uranium. Because of its atomicweight, valence, etc., it is now considered to be the second member of the actinide seriesof elements.
Thorium occurs in thorite and in thorianite. Large deposits of thorium minerals havebeen reported in New England and elsewhere, but these have not yet been exploited. Thoriumis now thought to be about three times as abundant as uranium and about as abundant aslead or molybdenum. Thorium is recovered commercially from the mineral monazite, whichcontains from 3 to 9% ThO2along with rare-earth minerals.