Using a floating zone technique and a passive afterheater, crack-free single crystals of manganese orthosilicate, Mn2SiO4, were grown along the three principle orientations in a reducing gas atmosphere at atmospheric pressure. The grown crystals were typically 5-7 mm in diameter and 20-40 mm in length. Well-developed facets were found on the periphery of some of the crystals grown along the [100] orientation (space group: Pbnm). Laue back reflection was used to determine orientations of grown crystals and of facets formed at outer surfaces. Dislocation densities ranging between 10(5) and 10(6) cm(-2) were determined by optical microscopy after polishing and chemical etching. By using X-ray powder diffraction it was determined that a thermodynamically favored decomposition of grown single crystals of manganese silicate during cooling after crystal growth did not occur. Concentrations of impurities and the degree of a desired silica excess present in the grown crystals were determined by using the ICP-AES technique. The presence of intended silica-rich precipitates was confirmed by electron microprobe analysis. (C) 2012 Elsevier B.V. All rights reserved.