Abstract: A process for the preparation of a superconductor of the type AB.sub.2 Cu.sub.3 O.sub.7-x, wherein A is a mixture of rare earths, B is an alkaline earth metal and x is less than one, comprising the treatment of xenotime to obtain a rare earths oxide therefrom and mixing the oxide with an alkaline earth metal compound and a copper compound and heat treating the mixture to obtain the superconductor. The treatment of the xenotime comprising melting the xenotime with a 1:1 mixture of Na.sub.3 CO.sub.3 and K.sub.2 CO.sub.3, dissolving a solid obtained therefrom in HCl, treating the resulting solution with NH.sub.4 OH to precipitate the rare earths, dissolving the precipitate in HCl, treating the resulting solution with H.sub.2 C.sub.2 O.sub.4 to precipitate the rare earths aned calcinating the precipitate to obtain a rare earths oxide.