Fig. 4

Frictional healing (∆μ) of clay minerals and quartz under wet conditions. Frictional healing systematically increases with holding time; however, clay minerals show a much lower healing rate than quartz. The slopes indicate healing rates of b = 0.014 for quartz, b = 0.004 for illite, and b = 0.001 for saponite and chlorite. The filled symbols indicate the experiments using pure water, and the open symbols indicate the experiments using 0.5 M NaCl water