Acicular bodies of a metal compound are produced by slowly precipitating an organic salt of the metal from a solution of an ester of a dicarboxylic acid having 1-5 carbon atoms and firing the precipitate in an oxidizing atmosphere. These acicular bodies have a cross-sectional dimension less than about 20 &mgr;m and are useful for providing reinforcement of a larger ceramic body. Acicular bodies of rare-earth metal oxides also are useful in reinforcing x-ray scintillator bodies without diminishing their luminescent capacity.