Preliminary reconnaissance in the Rocky Mountain (Lime Peak), Alaska, area by the Bureau of Mines and the University of Alaska indicates the Lime Peak pluton is a composite intrusion comprising at least three plutonic phases cut by two sets of north-trending dikes. Numerous occurrences of fault-controlled, tin-bearing greisen have been identified. The greisen is composed of quartz, chlorite, sericite, and minor amounts of fluorite, tourmaline, topaz, pyrite, chalcopyrite, and molybdenite; samples contain between 60 and 1,560 ppm tin. Because there has been no systematic sampling, the extent of the mineralization is unknown. Stream sediments and panned concentrate samples contain anomalous metal concentrations over a region that is generally coincident with outcrops of the Lime Peak pluton. Two anomalous drainage areas in addition to several isolated samples comprise the larger anomalous region. Anomalous concentrations of tin, tungsten, columbium (niobium), and thorium occur in sediment or panned concentrate samples collected from streams draining the Lime Peak summit whereas anomalous concentrations of lead, zinc, uranium, thorium, copper, tin, and beryllium occur in samples from streams draining the northeastern periphery of the pluton.