We request 5 days of beamtime on ENGIN-X to continue our investigation into the influence of relative grain size on stress partitioning between the constituent phases in two phase polycrystalline aggregates as they undergo plastic yielding. Our experiments will be performed on four calcite (CaCO3) + halite (NaCl) samples with the same composition and halite grain size but with calcite grain sizes varied between 5 and 200 microns. Our overall objectives are (1) to monitor the influence that relative grain size has on elastic strain partitioning in polymineralic geological materials, and (2) to examine how changes in relative grain size impact on the way that the deformation within the strong phase (calcite) is accommodated. This beamtime will test our hypothesis that increasing calcite grain size at constant volume fraction is equivalent to decreasing the calcite volume fraction.