Traditional X- ray methods being applied to soils samples allow to determine only main crystalline phases, resent in high quantities. This approach does not provide possibilities to determine exact mineral species in the groups and in particular diagnosis of polytypes in kaolinite, mica and chlorite groups. This arises difficulties in application of X- ray method in criminalistic soil investigations which need determination of all crystalline components taking into account their individual structural features.
Criminalistic research needs registration of no- basal reflections. For detailed diagnosis of clay minerals including determination of mica and chlorite polytypes in criminalistics method of scanning of reciprocal space of axial textures is suggested. This method allows separate registration of series of diffractional spectra from one object when each spectrum contains reflexes of definite type only.
Mineralogical composition of soils is an important diagnostic indicator to be used for determination of phases of larcenies from trains. The soils of the territories, adjacent to railways has a specific mineralogical composition. For example, they are characterized by high content of trioctohedral micas which are rare in the upper horizons of natural soils because of their low stability in conditions of intensive weathering. Differences in the ration of the polytypes of these minerals are determined dominantly by specific ways of transformation of micas in different technogenic environments and less by inheritance. That's why the investigation of peculiarities of mineralogic composition allows establishment of the exact place even on one railway station that helps much in disclosing of crimes.
In some cases the determination of chlorite polytypes in also useful. Thus, the differences in ratio of contents of 2b polytypes (the most wide spread) and lb ort (which is more rare) allows to establish difference in the source of the material even in case when basal reflections are similar.