"Rocks, Minerals, and Materials Science," a special session of the Geological Association of Canada and Mineralogical Association of Canada joint annual meeting, was convened in Fredericton, May 16, 1985, under the auspices of the Geological Association of Canada. The special session was supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) conference grant. The intention of the session was to foster a multidisciplinary approach to geological and mineralogical studies by bringing together researchers from classically divergent disciplines who nonetheless follow similar experimental approaches based on consideration of the physical and chemical processes responsible for the phenomena they study. Authors of contributed papers included mineralogists, petrologists, field and experimental structural geologists, material scientists, and physicists. Several of the papers follow.Although such unifying approaches are not new, it was appreciated by the organizers of the special session that there still exists in the geological sciences a tendency to fall back into established niches and to de-emphasize the usefulness of "cross-pollenating" ideas and methods. As indicated by the title, this approach is well recognized in nongeological studies, such as materials science, the principles of which are fundamental to everything from petrology (by way of ceramic phase chemistry) to modern structural geology (by way of the physics of polycrystalline deformation). Because of the relative simplicity of many nongeological materials systems, concepts and methods often have been developed for such systems first and then applied to more complex geological problems. This is well illustrated by the adaptation of electron microscopy to various geological studies to characterize atomistic and grain-scale processes and associated features. As emphasized in several of the included papers, the application of the materials-science approach is ultimately constrained by the unique geological problem of long and complicated chemical and physical histories, developed over an extreme range of temperatures, pressures, and chemical environments. The necessity for integrated field observations remains as always vital.