1911 Encyclopædia Britannica/Thorianite

THORIANITE, a rare mineral, discovered by W. D. Holland, and found in the gem-gravels of Ceylon, where it occurs as small, heavy, black, cubic crystals, usually much water-worn. It was so named by W. R. Dunstan, on account of its high percentage of thorium (about 70% ThO₂); it also contains the oxides of uranium, lanthanum, cerium and didymium. Helium is present, and the mineral is slightly less radio-active than pitchblende. It has been examined for new elements. Miss Evans (Journ. Chem. Soc., 1908, 93, p. 666) obtained what is possibly a new element, whilst M. Ogawa (Journ. Coll. Sci. Tokyo, 1908, vol. 25) found indications of three new species: one which he called nipponium, with an equivalent weight of about 50 and atomic weight 100; the second with an equivalent of about 16.7; whilst the third yielded a radio-active oxide.