Evaluation of the ac and dc characteristics of rock conductivity

Results are presented on the ac and dc characteristics of Wausau granite which show that excess ac losses at low temperatures are associated with cracks sealed by rutile, and are independent of any new open cracks. Data is also presented on the effect of surface hydration and contamination in old weathered cracks. Pyroxene was found to be the apparent major conducting phase in Mellen gabbro using a new scanning electron microscope technique.