Infrared spectroscopy is particularly good at identifying a wide variety of hydrothermally altered minerals with no sample preparation, and is especially helpful in discrimination among clay minerals. We have performed several promising pilot studies on geothermal drill core and cuttings that suggest the efficiency of the technique to sample continuously and provide alteration logs similar to geophysical logs. We have successfully identified layered silicates, zeolites, opal, calcite, and iron oxides and hydroxides in drill cuttings from geothermal wells. In high vertical resolution measurements (every 10’) we note depth-associated changes in alteration minerals, patterns or zones. This paper describes our results to date, noting distinct mineral assemblages related to system temperature.