This data set includes the U. S. Geological Survey MRDS (Mineral Resource Data System), current through November, 1994. These files have been exported from a Microsoft Access database used by the Arizona Geological Survey for accessing the MRDS data for Arizona. The data have not been reviewed for accuracy. A total of 4441 records are included in the data set. Figure 1 shows the distribution of sites for which there are records in the database. This collection of mineralized sites includes only a subset of known sites in the state (the U. S. Bureau of Mines MILS data set includes more than 10,000 sites in the state of Arizona). The completeness of data in each record varies widely. This data set is starting point, and will be updated periodically as more data is added from literature surveys and field investigations.