The variations of the structural state and clay minerals association provides the information on the sedimentation conditions, diagenetic alteration or weathering of rocks. Investigations of the XRD structural criterions of zonation, rate and direction of alteration of clay minerals, relation- ships between XRD characteristics of structural state of clay minerals variation and diagenesis of Late Paleozoician rock associations and weathering of various composition rock were studied. The complex quantitative and statistical criterions were used as probable indicators for evaluating of direction and degree of diagenesis and the rate of weathering of rocks.