Sandia National Laboratories is conducting and directing the MultiWell Experiment (MWX) core analysis program as part of the Western Gas Sands Project for the Department of Energy's Unconventional Gas Sands Program. Sandia National Laboratories will carry out sample selection, sample distribution, prioritization of analyses, distribution of data, and coordination of interagency analyses. The U.S.G.S., along with Sandia, will provide interpretation of analytical results. A sedimentological model of the Mesaverde Group at the Multi-Well site will be published by J.G. Lorenze (Sandia). The Petrology Laboratory of Bendix Field Engineering Corporation is providing routine mineralogic and petrologic analyses of MWX core samples and interpretations, as detailed in this report. These are preliminary results to be used primarily for characterization of the general mineralogy and textures of an interval so that variations in mineralogic trends can be delineated. This report is the fourth of fifteen which will present the results of petrologic analyses of the fifteen intervals to be submitted from drill holes MWX-l and 2. Included here are mineralogic and petrologic data from the Fracture Zone Interval of drill hole MWX-l.