This metal exists as an oxide in some rare minerals, e. g. to the extent of 73 3/4 per cent. in orangeite, 59 per cent. in thorite, and 18 per cent. in monazite, as well as smaller proportions in orthite and gadolinite. It is prepared in the metallic form by heating the chloride with a reducing agent, such as sodium or potassium. The chloride is first obtained by heating the oxide mixed with carbon in a current of . chlorine. The metal forms a grey powder, soluble readily in nitric and difficultly in hydrochloric acid, insoluble in aqueous alkalies, taking fire when heated in the air, and having a sp. gr. of about 7-7.