  Analysis of distortions of the crystal lattice within individual mineral
grains is central to the investigation of microscale processes that control and
record tectonic events. These distortions are generally combinations of lattice
rotations and elastic strains, but a lack of suitable observational techniques
has prevented these components being mapped simultaneously and routinely in
earth science laboratories. However, the technique of high-angular resolution
electron backscatter diffraction (HR-EBSD) provides the opportunity to
simultaneously map lattice rotations and elastic strains with exceptional
precision, on the order of 0.01 degree for rotations and 10-4 in strain, using
a scanning electron microscope. Importantly, these rotations and lattice
strains relate to densities of geometrically necessary dislocations and
residual stresses. Recent works have begun to apply and adapt HR-EBSD to
geological minerals, highlighting the potential of the technique to provide new
insights into the microphysics of rock deformation. Therefore, the purpose of
this overview is to provide a summary of the technique, to identify caveats and
targets for further development, and to suggest areas where it offers potential
for major advances. In particular, HREBSD is well suited to characterising the
roles of different dislocation types during crystal plastic deformation and to
mapping heterogeneous internal stress fields associated with specific
deformation mechanisms/microstructures or changes in temperature, confining
pressure, or applied deviatoric stress. These capabilities make HR-EBSD a
particularly powerful new technique for analysing the microstructures of
deformed geological materials.
