Crystal growth can be controlled by the incorporation of dopant ions into the lattice and yet the question of how such substituents affect the morphology has not been addressed. This paper describes the forms of calcite (CaCO3) which arise when the growth assay is doped with cobalt. Distinct and specific morphological changes are observed; the calcite crystals adopt a morphology which is dominated by the {01.1} family of faces. These experimental studies paralleled the development of computational methods for the analysis of crystal habit as a function of dopant concentration. In this case, the predicted defect morphology also argued for the dominance of the (01.1) face in the growth form. The appearance of this face was related to the preferential segregation of the dopant ions to the crystal surface. This study confirms the evolution of a robust computational model for the analysis of calcite growth forms under a range of environmental conditions and presages the use of such tools for the predictive development of crystal morphologies in those applications where chemico-physical functionality is linked closely to a specific crystallographic form. (C) 2002 Published by Elsevier Science B.V.