The salt rock samples in this experiment were collected from depths of 1000 m at sites in the Himalayas. The rock has a high content of NaCl (more than 96%), small amounts of K2SO3, and some mud. To ensure the similarity of the salt rock samples as much as possible, samples with almost the same content of impurity and without cracks were selected. The salt rock samples were cut into circular cylinders 50 mm diameter 100 mm length, and the evenness of the head faces was controlled to 0.02 mm. Appropriate measures were taken to protect the salt rock speci- mens from fatigue damage during processing. We assume that all the samples were subjected to similar processing damage; there- fore, the effect on the test results would be minimal.