The coalescence growth process of a joint cloud of fine smoke particles evaporated from Fe and those from S produces fine grains of pyrrhotite, in addition to stoichiometric troilite and marcasite. Pyrrhotite grains exhibited a typical DDSS (diffusion-dependence shell structure) shape produced by diffusion of iron atoms to the surface layer. Various superstructures of pyrrhotites were observed by changing the heater temperature. An outline of the experimental procedures of coalescence growth formation of iron sulfide and the main experimental results are described. Magnetic properties of some carbonaceous chondrites have been summarized and discussed in comparison with the characteristics of the coalescence product