Geologic map of bastnaesite deposits, Birthday claims, San Bernardino County, California

In April 1949 a deposit containing considerable quantities of the rare mineral bastnaesite - the fluorocarbonate of cerium, lanthanum, and other rare earths - was discovered near Mountain Pass, San Bernardino County, Calif.  Small quantities of bastnaesite have been found in several places in the United States, but this area is the first that offers promise of being a commercial source of cerium, lanthanum, and other rare earths.