Alkali halide crystals doped with divalent materials like SnS, SnSe and SnTe where investigated by means of optical spectroscopy. Using SnSe in KCl as an example it is shown that SnSe-molecules substitute pairs of an anion and a cation vacancy and that samples grown from the melt also contain dimers like (SnSe)(2). Thermal annealing above 500 degrees C results in the formation of scattering centers which are believed to be microcrystals of semiconducting SnSe in an alkali halide matrix.