  We report the growth of mm-sized Pmnb-Li2FeSiO4 single crystals by means of
the optical floating-zone method at high argon pressure and describe the
conditions required for a stable growth process. The crystal structure is
determined and refined by single-crystal X-ray diffraction. The lattice
constants amount to a = 6.27837(3) A, b = 10.62901(6) A and c = 5.03099(3) A at
100 K. In addition, we present high-resolution neutron powder diffraction data
that suggest that the slight Li-Fe site exchange seems to be intrinsic to this
material. High quality of the crystal is confirmed by very sharp anomalies in
the static magnetic susceptibility and in the specific heat associated with the
onset of long-range antiferromagnetic order at TN = 17.0(5) K and pronounced
magnetic anisotropy for the three crystallographic axes. Furthermore, magnetic
susceptibility excludes the presence of sizable amounts of magnetic impurity
phases.
