Abstract: Granitic samples from Zhejiang Province, Southeast of China, were tested in a uniaxial condition to failure at constant confining pressure. It is found from careful Scanning Electron Microscope (SEM) observations that fractures form the intersection or coalescence of microcavities. Granite consists of three major minerals, Quartz, feldspar (K-feldspar &Plagioclase) and biotite. The cracks in various minerals of the specimen develop differently; this obvious difference in crack patterns is believed to result from the nature of their microstructures. Careful observation shows that quartz display brittle and isotropic crack while feldspar and biotite exhibit anisotropic cracks and the separating of their cleavage planes (cleavage cracks) is the one of the major failure forms of biotite and feldspar. From the tectonic point of view, the granite has been strongly deformed and hydrothermally altered; such hydrothermal fluids may be keep the system open for fluid movement to cause alteration metasomatism of granite.