"The Los Alamos National Laboratory, in cooperation with Science Applications, Inc (SAI), supported several series of oil shale fragmentation experiments sponsored by a consortium of oil companies. These experiments, executed at the Anvil Points Mine in Garfield County, Colorado, have contributed to a better understanding of the fracture characteristics and fragmentation of in situ oil shale by conventional high explosives. The experiments have also allowed a comparison of results to those from previous experiments performed in corresponding stratigraphic layers at the Colony Mine several kilometers away. The Anvil Points Mine presented the opportunity to locate similar experiments in different grades of shale to determine the influence of kerogen content on rubblization. Geologic site characterization included coring at selected locations in the mine, preshot mapping, postshot crater inspection, and screening of crater rubble. Evaluations of the data show that effectiveness of the energy from the detonation is greatly dependent on the grade of the host shale. This influence combines with that from natural joint systems to produce experiment results that are distorted by natural geologic features at the site. This influence from site geology is expressed primarily in the resulting fragment size distribution and crater asymmetry. The grade appears to be the single most important factor influencing the ultimate mix of rubble sizes from these experiments. The geologic complexity of the site, which controls crater asymmetry, becomes progressively more influential with increased values for the scaled depth of burial (SDOB). Thus, the geologic complexity of a site interacting with the SDOB is important to shothole spacing, pattern, and orientation. Also, a non-dimensional performance parameter, designated as A, was derived to allow the comparison of rubble size for all the experiments normalized to grade, SDOB, and spacing. This relationship, along with the grade of the shale to be rubbled, may eventually be used to deduce general values for spacing and SDOS that would produce a desired distribution of rubble size. The Anvil Points Mine experiments underscore the significant role of geology in high explosive/oil shale interaction. The influence of site geology will require consideration for designing explosive configurations for larger retort applications."