Scanning electron microscope pictures of ground and lapped ferrite (sinfered magnetic ceramic) and steel surfaces and chips are studied and compared. These reveal considerably more plastic action associated with the formation of metal chips in fine grinding than for ferrite chips. Individual chips are an order of magnitude larger for metals than for ferrites. These results are consistent with the much greater specific grinding energy for metals than for ferrites. The depth of the plastically deformed layer beneath a ground surface revealed by etching corresponds closely with the depth of residual surface stress.