Good quality single crystals of high purity cobalt silicate, Co2SiO4, were successfully grown by the floating-zone method in air at atmospheric pressure along the three principle orientations. The grown crystals were 30-60 mm in length and 6-10 mm in diameter. Well developed facets were found on all crystals grown. Impurity levels and the degree of a desired excess of silicon in grown crystals were determined by using the ICP-AES technique. In addition, the presence of a small amount of inclusions in the matrix of grown crystals due to a small excess of silica was confirmed by TEM. Dislocation densities were determined upon etching; the observed densities were on the order of 10(5)-10(6) cm(-2). (C) 2011 Elsevier B.V. All rights reserved.