The clasts recovered from the South Chamorro serpentine mud volcano during Leg 195 have very narrow density and velocity ranges and a low microcrack content. The velocity-density relationships exhibit the linear trend established by Christensen (1966). The densities, velocities, and Poisson's ratios of the rocks all suggest very high percentages of serpentinization in the rocks. A comparison of the degree of serpentinization in these clasts compared to the serpentinization calculated from the Izu-Bonin seismic study conducted in a setting similar to the South Chamorro Seamount shows that these clasts experienced more serpentinization than the forearc wedge. In general, these velocity and density measurements may be used in future seismic and gravity studies to help constrain the lithologies and serpentinization at these subduction zones.