Reaction of Bullfrog tuff with J-13 well water at 90{sup 0}C and 150{sup 0}C

A series of experiments was conducted on crushed tuff at 90{sup 0}C and 150{sup 0}C and on core wafer samples at 150{sup 0}C. The results show the following: increasing the ratio of rock to water increases the rate of approach to steady-state concentrations in solution. Surface outcrop samples of Bullfrog tuff contain a minor component of highly soluble material believed to be a residue from the evaporation of surface runoff water in the pores of the rock. This material can be removed by shaking the crushed rock with water at room temperature and subjecting it briefly to heat with fresh water. Solution analyses for unfiltered samples that have reacted for short periods show higher concentrations of Al and Fe than do analyses for filtered samples; results for other elements are independent of filtration. This difference probably exists because of particulate matter in the solutions that dissolves when the samples are acidified prior to analysis. Agitation of samples during reaction produces sub-0.1 {mu} particles in the solutions. These particles dissolve when samples are acidified, resulting in abnormally high concentration values for some elements, such as Al and Fe. Comparison of the results for crushed rock with those for core wafers shows that the method of sample preparation does not have a large effect on the results of rock-water interaction studies