Atomic force microscopy (AFM) has been used to study the growth mechanism of the manganese mercury thiocyanate (MMTC) crystal. Two-dimensional (2D) nucleation growth mechanism dominates on the {1 1 0} faces. 2D nuclei introduced growth islands and steps with wavy fronts are investigated. Nucleation on the wider step terraces results in the overhang morphology of steps. With growing of the surface, initial faulty connection of 2D nuclei may lead to formation of long deep tubes with liquid inclusions. Further crystallization of liquid inclusions occurs via 3D nucleation mechanism. (c) 2005 Elsevier B.V. All rights reserved.