432 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



BLAINE COUNTY 



Scorodite occurs in the ore of the Golden Bell mine in the intrusive 

 granodiorite at the head of Minnie Gulch in the Hailey district. 

 It forms an incrustation in the oxidized portion of the vein. 34 



CASSIA COUNTY 



Scorodite occurs in some abundance associated with cinnabar in 

 prospects near Black Pine in Cassia County. 35 The scorodite is 

 blackish olive green in color with a small botryoidal surface. It 

 shows no evidence of crystal form, and the interiors of the botryoidal 

 masses are compact with a subconchoidal fracture and no trace of 

 cleavage. The mineral is translucent and the luster is somewhat 

 greasy. The fracture is difficult, the material being very tenacious. 

 The specific gravity as determined on a fragment by the Kraus 

 modified Joly balance is 3.016. An analysis of the scorodite yielded 

 the following results : 



Analysis oj scorodite from the Black Pine district 



(E. V. Shannon, analyst) 



Per cent 



Insoluble 0. 32 



Arsenic pentoxide (As 2 5 ) 44. 40 



Phosphoric acid (P 2 5 ) 4. 80 



Ferric iron (Fe 2 3 ) 34. 02 



Lime (CaO) Trace. 



Magnesia (MgO) Trace. 



Alumina (A1 2 3 ) Trace. 



Chromium oxide (Cr 2 0-3) . 32 



Water (H 2 0) above 110° C 12. 25 



Water (H 2 0) below 110° C 5. 08 



Total 101. 19 



LEMHI COUNTY 



Scorodite is apparently common or abundant in the Blackbird 

 district, in Lemhi County, where it has passed under the name 

 "nickel bloom," apparently being mistaken for annabergite. Yellow 

 green earthy material surrounding residual nuclei of cobaltite in 

 quartz of a specimen from the Nickel Plate mine is probably scoro- 

 dite. It reacts qualitatively for arsenic and ferric iron. Under the 

 microscope the material is faintly birefracting to amorphous isotropic 

 with an index of refraction of about 1.74. The scorodite of this 

 specimen is associated with olivenite. 



A specimen from the Alpha claim, top of the hill, Blackbird dis- 

 trict. This specimen, which was labeled "Nickel bloom," is said 

 to be typical of a great deal of float on the top of the divide scattered 



31 D. F. Hewett. Oral communication. 



« E. S. Larsen. Univ. of Idaho School of Mines, Bull. 2, pp. 65-67, 1920. 



