Note: Do not rely on this information. It is very old.
Gadolinite, a rare mineral, which was discovered by Gadolin, in 1788, at Ytterby in Sweden. It forms monoclinic crystals, and is interesting as the source of many of the rarer chemical elements, viz.: - Yttrium, which it contains to the extent of 35 per cent.. Ytterbium, Scandium, frequently, also, Erbium, Cerium, Didymium, and Lanthanum; while sometimes Beryllium is found among its constituents.