THE MINERALS OF IDAHO 169 



BOISE COUNTY 



Stephanite occurred abundantly in quartz with pyrargyrite and 

 cerargyrite in a silver vein which was found 40 feet north of the gold 

 vein on the Washington claim, Idaho City district. 55 In a specimen 

 of ore from this locality the mineral, which is brilliant gray with good 

 cleavage, occurs plastered around quartz crystals in minute combs. 

 In specimens from the tunnel level, Banner mine, Banner district, 

 fine dark steel gray masses which are probably stephanite occur with 

 pyrargyrite, coarse granular sphalerite, and some pyrite, between 

 crystals of interlocking quartz combs in narrow veins in altered 

 granite. 



ELMORE COUNTY 



In Elmore County stephanite has been the most abundant and 

 important ore mineral in the rich silver ores of the Atlanta district. 

 The mineral occurs as granular, imperfectly crystalline, and columnar 

 black masses associated with a less amount of pyrargyrite in comb 

 quartz. Often the pyrargyrite forms lines along the sides of narrow 

 veins while the centers are filled with stephanite (Cat. No. 51864, 

 U.S.N. M.). In some specimens the stephanite occurs as grains with 

 pyrargyrite in coarse granular galena. (Cat. No. 30199, U.S.N.M.). 

 In the Atlanta lode stephanite was the most abundant ore in the 

 bonanza deposits; next in quantity came pyrargyrite, while argentite, 

 stromeyerite, and native silver were present in relatively small quan- 

 tities. "The rich streak of black stephanite and ruby silver varied 

 in width from 1 foot to 6 or 7 feet, alongside which was a band of 

 similar width of payable ore containing free gold with disseminated 

 silver minerals, making the workable vein from 2 to 15 feet wide and 

 extending in length underground in the Monarch and Buffalo claims 

 nearly 2,000 feet on the course of the lode." 5 l 



OWYHEE COUNTY 



Stephanite is prominent in the ores of the Flint district, being 

 reported by J. Ross Browne early in the history of the district. It is 

 to be found in specimens collected from the Rising Star and other 

 mines within recent years. 



POLYBASITE (156) 



Silver sulphantimonite, 8Ag 2 S.Sb 2 S 3 . Monoclinic, perihexagonal. 



Polybasite is probably a common mineral in many of the silver ores 

 of the State and has been reported from a number of districts. It is 

 to be noted, however, that most of the identifications of the mineral 

 are made upon visual characteristics only and are in need of con- 



" Waldemar Lindgren. 18th Ann. Rept. U. S. Geol. Survey, pt. 3, pp. 688-689, 1897. 

 »• Joshua E. Clayton. Trans. Amer. Inst. Min Eng., vol. 5, Feb. 1877, pp. 468-473. 



