The diffusion of some metals of the group A-II, of the periodic table of the elements inside a milky silica gel containing carbonate ions produces highly atypical precipitates characterized by their singular morphology. The precipitate is a self-assembled nanocomposite material with two clearly distinct phases: an amorphous (from silica gel) and a crystalline metal-carbonate phase. These materials usually called induced morphology crystalline aggregates (IMCA) represent a plausible model for experimental simulations and for the understanding of biomineralization processes in nature. In this contribution, we show how these aggregates are obtained. We also show how the typical morphology is modified due to the influence of 20 L-amino acids that are usually present in proteins. We have also introduced the first structural characterization using atomic force microscopy and image analysis in order to describe the IMCA from the theoretical and the experimental point of view. Finally, the results are compared with those images found in nature formed by means of biomineralization in living organisms (such as calcite crystals present in avian eggshells). (C) 2002 Elsevier Science B.V, All rights reserved.