Buddingtonite in Menlo Park, California

The mineral buddingtonite, named after A.F. Buddington, long-time professor of petrology at Princeton University, was first identified at the Sulfur Bank mine in Lake County, California (Erd and others, 1964). The ammonium feldspar was recognized in Menlo Park, California, in 1964 by the author, with Erd's help, shortly before publication of the original description of the new mineral. Subsequently, buddingtonite has been widely recognized in hydrothermal mineral deposits and has been used in remote-sensing applications by the mineral industry. Buddingtonite also has been identified in the Phosphoria Formation and in oil shales of the Green River Formation. This paper briefly describes the geologic setting and mineralogy of the occurrences of buddingtonite and other ammonium-bearing minerals in the vicinity of Menlo Park.