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The slip behavior of major faults depends largely on the frictional and hydrologic properties of fault gouge. We report on laboratory experiments designed to measure the strength, friction constitutive properties, and permeability of a suite of saturated clay‐rich fault gouges, including: a 50:50% mixture of montmorillonite‐quartz, powdered illite shale, and powdered chlorite schist. Friction measurements indicate that clay‐rich gouges are consistently weak, with steady state coefficient of sliding friction of <0.35. The montmorillonite gouge (μ = 0.19–0.23) is consistently weaker than the illite and chlorite gouges (μ = 0.27–0.32). At effective normal stresses from 12 to 59 MPa, all gouges show velocity‐strengthening frictional behavior in the sliding velocity range 0.5–300 μm/s. We suggest that the velocity‐strengthening behavior we observe is related to saturation of real contact area, as documented by the friction parameter …