in pegmatitic feldspars from the southern Black Hills, South Dakota
G. Cleve Solomon, George R.
Division of Geological and Planetary Sciences
California Institute of Technolgy, Pasadena, CA
Trace amounts of ammonium ion (0.7 mol% NH4+
substitution) have been identified from the infrared spectra of alkali
feldspars from pegmatites occurring in the southern Black Hills
district, South Dakota. The spectroscopic data indicate that the
ammonium is structurally bound, most likely in the M site of the microcline. These
results indicate that ammonium was likely a component of metamorphic
fluids present during anatexis of metasedimentary rocks in the southern
Black Hills district.
American Mineralogist 73, 818-821