Deformation experiments of Hale albite rock have produced faults at 5 to 15 kb confining pressure and 700 ¿ to 1125 ¿C, when hydrolytic weakening is suppressed by either the absence of water or by low pressure. The faults are characterized by : 1) an angle of about 45 ¿ to s1, 2) very little gouge, and 3) several percent permanent strain before failure. Temperature dependent friction is believed to allow frictional sliding and faulting at stresses below those predicted by the Coulomb failure criterion, but above those of hydrolytically weakened crystal plastic flow. High confining pressure, low friction and reduced tensile stress concentrations may allow the fault to propagate as a shear rather than a tensile crack.