Abstract
Uniaxial tensile fractures parallel to each anisotropic plane in Inada granite has been investigated by direct observations and under microscope. Many part of the fractures split the rock-forming mineral grains, and only about 10 percent of them follow grain-boundary cracks. The fracture surface parallel to the rift plane have almost same constituent mineral ratio as the parent rock. However the fracture, parallel to the grain and hardway planes, prefer feldspar grains and cut across less quartz than the parent rock. It's especially remarkable in the fracture parallel to the hardway plane. The different surface mineral ratios of fractures parallel to each plane are caused by preferred orientations and distributions of microcracks in quartz and feldspar.
