Pegmatites of Southern California

For many years the southern California region has attracted the attention of geologists interested in pegmatites and pegmatite deposits, largely because of the well-known gem and lithium occurrences in San Diego and Riverside Counties. These world-famous pegmatites have been so often noted or described in the literature that they commonly are regarded as typical of the pegmatites in the region, even though this actually is far from the case. More than 90 percent of all published contributions on California pegmatites deal with the gem-bearing dikes of San Diego County alone! It is the main purpose of this brief paper to summarize the distribution, occurrence, composition, and structure of all the known pegmatites in southern California, and to discuss several aspects of their geologic and economic significance. Much of the information has been obtained from the published record, a sampling of which is included in the list of references at the end of the paper. In larger part, however, the writer has found it necessary to draw from the results of his own observations, many of which were made in reconnaissance and hence are not wholly satisfactory as a background for generalizations. This qualification with respect to basic data plainly underlies the summary and discussions that follow.