Clarence Samuel Ross (20 September 1880, Eldora, Iowa – 19 April 1975, Rockville, Maryland) was an American mineralogist, petrologist, and economic geologist.
The survey first assigned him the task of mapping oil lands in Osage County, Oklahoma, where he studied bentonitic key horizons.
In 1919, with Esper S. Larsen, Jr., he made geologic maps of the southern end of the San Luis Valley in New Mexico.
His early studies with Hugh D. Miser were made on the diamond-bearing peridotite in Pike County, Arkansas, and are models of description and interpretation.
[1]Ross's versatility and broad range of interests are shown by the major topics listed in his bibliography of 121 titles: they covered mineralogy and occurrence of clay minerals, geology of copper deposits of the Southern Appalachians, petrology of rhyolitic welded tuffs, mineralogy and petrology of titanium deposits in Virginia, and comparison of peridotite and pyroxenite with ultramafic nodules in basalts.