  The movement and deformation of mineral grains in rocks control the failure
behavior of rocks. However, at high resolution, the physical and mechanical
behavior of three-dimensional microstructures in rocks under uniaxial
compression has not been characterized. Here, in suit XCT (4.6 um) has been
applied to investigate the behavior of mineral grains of sandstone -- movement,
rotation deformation and the principle strains obtained by deformation gradient
tensor constructed with three principle axial vector representation of grain,
indicating that the behavior of grains between the fracture and the
non-fracture zone are different. For further investigate the behavior of grain
cluster, the material lines are used to obtain the Stokes local rotation,
namely shear strain. The finding is that: 1. the shear strain is periodic in
the radial direction. 2. on average sense, the positive shear strain and
negative shear strain have local concentration features.
