Visualization of the failure of quartz under quasi‐static and dynamic compression

Quasi‐static and dynamic compression experiments were performed on natural α quartz single crystal specimens at strain rates ranging from 10 −3 to 10 3 s −1 using a high‐speed camera for visualization of failure. In one set of experiments, the specimens were compressed until catastrophic failure occurred, shattering the specimen into many small pieces. The results of the experiments show little strain rate dependence of the compressive strength of quartz for the range of strain rates applied in this study. In a second set of experiments, referred to here as interrupted compression, the specimens were compressed to a stress level of about half of the failure strength and then unloaded. For times up to when the peak load is achieved, images of the specimen recorded during the experiment show no crack initiation or propagation. However, in these experiments, the growth of large planar cracks was observed during (and only during) the unloading phase. The real‐time visualization demonstrated that behavior of failure during unloading occurs in both the quasi‐static and dynamic interrupted compression experiments. The crystallographic indices of the failure planes were identified to be of the and families, indicating cleavage failure on the positive and negative rhombohedral surfaces, respectively.