Mixed-Layer Kerolite/Stevensite from the Amargosa Desert, Nevada

Dennis D. Eberl, Blair F. Jones and Hani N. Khoury
U.S. Geological Survey, Denver Federal Center, Denver, Colorado 80225
U.S. Geological Survey, National Center, Reston, Virginia 22092
Department of Geology and Mineralogy, University of Jordan, Amman, Jordan

Abstract: Mixed-layer clays composed of randomly interstratified kerolite/stevensite occur as lake and/or spring deposits of probable Pliocene and Pleistocene age in the Amargosa Desert of southern Nevada, U.S.A. The percentage of expandable layers of these clays, determined from computer-simulated X-ray diffractograms, ranges from almost 0 to about 80%. This range in expandabilities most likely results from differences in solution chemistry and/or temperature at the time of formation. An average structural formula for the purest clay (sample P-7), a clay with about 70% expandable layers, is: [ ( Mg 2.72 Al 0.07 Fe 0.03 Li 0.09 )( Si 3.96 Al 0.04 ) O 10 ( OH ) 2 ] −0.21 [ X + ] +0.21 . The data suggest that talc, kerolite, and stevensite form a continuous structural series based on layer charge.

Key Words: Hectorite • Kerolite • Layer charge • Mixed layer • Smectite • Stevensite • Talc

Clays and Clay Minerals; October 1982 v. 30; no. 5; p. 321-326; DOI: 10.1346/CCMN.1982.0300501
© 1982, The Clay Minerals Society
Clay Minerals Society (www.clays.org)