Structural Analysis of the Fracture Surface of a Heterogeneous Body (Quartz Sandstone)

The structure of surface layers of quartz sandstone with a thickness of similar to 1 mu m before and after destruction by a compressive stress is studied by methods of infrared, photoluminescent, and Raman spectroscopy. Before destruction, this layer contained quartz grains cemented with montmorrillonite and kaolinite. The grains are covered with a thin water layer and have crystallographic defects: Si-O-, self-trapped excitons, AlOH and LiOH compounds, [AlO4](-) centers, etc. The destructed surface contains separate quartz grains with sizes of similar to 2 mu m and a reduced defect concentration. It is assumed that the defects reduce the strength of quartz grains, which are destroyed in the first turn.