Mineral resource potential map of the Raywood Flat Roadless Areas, Riverside and San Bernardino counties, California

Geologic, geochemical, and geophysical studies within the Raywood "Flat Roadless Areas, together with an investigation of mines and prospects within the further planning area, resulted in (1) identification of nonmetallic mineral resources at a marble mine in the further planning area and (2) recognition of a small area in the recommended wilderness that has moderate potential for base-metal resources. Except for these two areas of identified and suspected resources, we did not observe indications of resource potential elsewhere in the Raywood Flat Roadless Areas.

The area having nonmetallic mineral resources is in the vicinity of the Mill Creek mine near the northeastern boundary of the further planning area (B5-187); there, we identified marginal reserves of marble suitable for the production of lime and construction stone. The reserves are marginal because of their remote location and poor accessibility. Geologic mapping did not reveal any additional marble occurrences within the study area.

The area having moderate potential for base-metal resources forms a small zone in the eastern part of the recommended wilderness (A5-187). Within this zone, evidence provided by stream-sediment geochemistry suggests that crystalline bedrocks in several drainages contain concentrations of metallic elements. Because the terrain is inaccessible and covered with dense brush, most of the bedrock in the specific drainages containing the geochemical anomalies could not be examined. Thus, although we infer that mineral occurrences exist in the drainage basins, we have little data on which to base an estimate of their extent and quality. Locally, the crystalline rocks probably contain hydrothermal veins or disseminated occurrences where lead, copper, molybdenum, tin, cobalt, bismuth, and arsenic have been concentrated. However, the geochemical anomalies for these metals are small, and the stream drainages also are relatively small. Therefore, the inferred occurrences of metallic minerals probably are small scale, scattered, and low grade. There is only low probability that the inferred mineral occurrences are large scale.