The mineralogical compositions of representative samples of air-drilled cuttings taken at 10-ft. intervals from 2 wells in the Punxsutawney-Driftwood gas field of central Pennsylvania have been determined by routine methods of X-ray analysis. Distinct mineralogical zones were found to correspond closely with formations and formational contacts. Although the wells are 18 mi. apart, correlations can be made. Compositional logs of air-drilled holes are easily obtained and can be used for interpreting sub-surface geology in the same fashion as conventional electric logs. In addition, the presence, absence, and relative abundance of minerals yield information on the geological history of the area.