174 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



containing finely disseminated argentite. In the Poorman mine it 

 is common as films in granular quartz and in spongy quartz con- 

 taining steaks of disseminated argentite. In the bonanza surface 

 ores of the Poorman lode remarkable amounts of cerargyrite were 

 found. The mineral occurred in sheets along both walls of the vein 

 and slabs a foot square and one-sixteenth of an inch thick could be 

 peeled off. Masses weighing many pounds were frequently obtained. 6 * 

 It was often well crystallized and in some cases the crystals were 

 half an inch across. These were mostly cubes and cuboctahedrons 

 but occasionally with other planes and in twins consisting of inter- 

 penetrating cubes, the angles of one projecting from the faces of the 

 other. 65 Exceptionally fine specimens from this remarkable occur- 

 rence have fortunately found their way into the Yale University 

 collection and thus have been preserved. Horn silver occurred in 

 the De Lamar and adjacent mines and in ore from the Laxley mine, 

 South Mountain district, the chloride occurs in altered spongy 

 matrix with malachite and bindheimite stains. 



SHOSHONE COUNTY 



Cerargyrite has never been definitely identified from any locality 

 in the Coeur d'Alene district, although it is quite probably present 

 in the richer oxidized lead silver ores. Miners in this district often 

 call any yellowish colored mineral " chlorides," particularly ocherous 

 bindheimite, pyromorphite, and in one case, greenish scorodite. 



EMBOLITE (170) 

 BROMIDE OF SILVER 



Silver chloride-bromide, AgCl. AgBr. Isometric. 



The chlorobromide of silver which usually occurs in soft wax-like 

 films, grains, or crusts resembling cerargyrite or horn silver, but 

 having a yellow or yellow-green color, has not been certainly identified 

 in Idaho. Bromide of silver has been reported from a number of 

 localities, as, for example, the Little Giant vein in the Warren district 

 in Idaho County, 66 but no specimens have been available for ex- 

 amination and it is not known whether the mineral is embolite or 

 bromyrite, both of which are commonly called bromide of silver. 

 Bromides of silver are reported by miners and prospectors from many 

 districts, but these reports arc not reliable, as western miners use the 

 term " bromides" indiscriminately to indicate any greenish or 

 bluish colored silver bearing material. Such "bromides" are in 

 most cases earthy cerargy rite-bearing oxidized ores stained by 

 copper compounds. 



61 J. Ross Browne. Mineral Resources of United States, 1867, p. 523. 



65 E. S. Dana. System of Mineralogy, p. 158, 1895. 



M Waldemar Lindgren. U. S. Qeol. Survey, 20th. Annual eport, pt. 3, p. 246, 1900. 



