Several underground coal gasification experiments have been conducted in the Hanna No 1 coal seam. During the fall of 1980 the Laramie Energy Technology Center performed a post-burn field study of the Hanna II, Phases 2 and 3 experiment at the Hanna UCG site. The field work consisted of high resolution seismic, drilling, coring, and geophysical logging. The Department of Earth Resources, Colorado State University, contributed to the post-burn study by doing laboratory work on the cores and geophysical logs. Funding was provided by the Laramie Energy Technology Center. The purpose of the laboratory work was to provide an estimate of the temperatures and chemical conditions reached during the conversion experiment by studying the mineralogic and textural characteristics of thermallly altered and unaltered overburden.