Parting of Minerals

the ability of mineral crystals or crystalline grains to split along certain more or less parallel planes. The parting of minerals differs from mineral cleavage in that the splitting occurs at points of irregularity in the mineral’s structure. The planes of mineral parting may be the boundaries of twinning, shear joints created by the mechanical deformation of crystals, or planes caused by parallel microintergrowth of fine layers of one mineral in another. Mineral parting occurs in corundum, hematite, the pyroxenes (diallage), pyrite, and magnetite.