460 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



the United States Geological Survey of a cut 4 feet across the bed 

 gave the following results : 



Analysis of gypsum, (bed) near Montpelier 



(W. C. Wheeler, analyst) 



Per cent 



Silica (Si0 2 ) 4. 14 



Alumina (A1 2 3 ) . 89 



Ferric iron (Fe 2 3 ) . 10 



Magnesia (MgO) . 99 



Lime (CaO) 31. 40 



Carbon dioxide (C0 2 ) 2. 33 



Sulphur trioxide (S0 3 ) 41. 13 



Water (H 2 0) loss at 200° C 18.39 



Total 99. 37 



In the mountains, in the northeastern part of Bear Lake County, 

 Mr. G. R. Mansfield found lenses and layers of gypsum in the nugget 

 sandstone of Jurassic or Triassic age, but nowhere more than a few 

 inches thick. 60 



CUSTER COUNTY 



In the Alder Creek (Mackay) district gypsum occurs as veinlets 

 in the oxidized ore and in the adjacent wall rock. Few of the veinlets 

 exceed a centimeter in width and many are less than a millimeter 

 across. The mineral also occurs as irregular grains sparsely scattered 

 in the oxidized ore. 61 



ELMORE COUNTY 



Samples showing abundant flakes and imperfect crystals of selenite 

 scattered through clay have been sent to the National Museum by 

 B. Z. Smith from Mountain Home. 



OWYHEE COUNTY 



Gypsum occurs in small amounts in soils with soluble sulphates, 

 nitrates, etc., in niter claims on Jump Creek and elsewhere southeast 

 of Homedale, Oreg. Gypsum, gypsiferous clay, and gypsiferous sand 

 have been encountered in the Claytonia saline claim west of the 

 Mc Cloud ranch (pi. 30, lower). 62 



WASHINGTON COUNTY 



Gypsum occurs with copper sulphate in oxidized silver ore of the 

 Silver Bell mine in the Mineral district. 63 



A gypsum deposit in Washington County lies high in the bluffs of 

 Snake River 10 miles northeast of Huntington, Oreg. Rock gypsum 



60 R. W. Stone and others. U. S. Geol. Survey Bull. 697, p. 99, 1920. 

 «» J. B. Umpleby. U. S. Geol. Survey, Prof. Paper 97, p. 53, 1917. 

 62 Q. R. Mansfield. U. S. Oeol. Survey, Bull. 620, p. 30, 1916. 



•' Waldemar Lindgren. Silver mines of Mineral, Idaho. U. S. Geol. Survey, 22d Ann. Rept., pt. 2, 

 p. 755, 1901. 



