U.S. DEPARTMENT OF THE INTERIOR 
U.S. GEOLOGICAL SURVEY

Open-File Report 01-72: This report is available as a pdf file. 
 It can be can be opened and read using Adobe Reader. 
 A free copy of Adobe Reader 5.0 can be downloaded at
 http://www.adobe.com/products/acrobat/readstep.html.  
The web-ready pdf file was prepared by John Wallis.
 Dave Frank and Carolyn Donlin also contributed to completion
 of this on-line version of the report.

TITLE:   " Preliminary Mineralogical Characterization of Weathered
 and Less-Weathered Strata of the Meade Peak Phosphatic Shale Member
 of the Permian Phosphoria Formation: Measured Sections C and D,
 Dry Valley, Caribou County, Idaho"
 by Andrew C. Knudsen, Mickey E. Gunter, and James R. Herring,
 Western U.S. Phosphate Project, 2001.

This 70-page report contains a narrative with six figures and four tables. 
 The study employed powder X-ray diffraction, with Rietveld quantification
 software to quantify and characterize the mineralogy of the 83 samples
 collected from two stratigraphic sections measured by the U.S. Geological
 Survey at the Dry Valley mine in the Meade Peak Member of the Phosphoria
 Formation.  Analyses show extensive variability of carbonate substitution
 in the fluorapatite structure, determined by measuring the apatite a-cell
 dimension, as well as patterns of correlation between mineralogy and the
 stratigraphy.     

The report is preliminary and has not been reviewed for conformity with U.S.
 Geological Survey editorial standards or with the North American
 Stratigraphic Code.  Any use of trade, product, or firm names is for
 descriptive purposes only and does not imply endorsement by the U.S. Government.

ACKNOWLEDGEMENTS:  The authors appreciate the help and participation of the
 Bureau of Land Management, the Forest Service, and staff at the
 Dry Valley mine, Astaris LLC.