The major issue addressed in the report is the relationship between cavity-material characteristics and ground-water impacts. Samples from the Tono excavation cavity were characterized by various analytical methods. Results indicate the unaltered coal mineralogy consisted of quartz, clay minerals, and feldspars, with some calcite, pyrite, gypsum, and zeolite. Of the altered material, char exhibited a similar mineralogy with a slight increase in gypsum, a loss of pyrite, and the appearance of some higher-temperature minerals. Data suggest that most ground-water contamination generated by leaching in a UCG cavity will be derived from char and the altered clay, carbonate, and sulfurous minerals contained within the char.