Project Cabriolet, a nuclear detonation in hard, dry (volcanic) rock, was executed as a part of the Plowshare Program for development of nuclear excavation techniques. The primary objectives of this experiment were: (a) to obtain experimental data on crater development and size in order to verify recently developed rock-mechanics computer codes and calculational techniques; and (b) to study the distribution of the radioactivity produced by the detonation in order to enhance the understanding of how the shot environment may affect this distribution. As was observed in the Danny Boy experiment, a relatively small amount of radioactivity was released to the environment from this detonation in hard, dry rock. Less than the equivalent of fission products from 10 tons of fission were distributed in both fallout and cloud from the Cabriolet experiment. As more data are reduced, a better description of the chemical fractionation associated with this released radioactivity will be possible.