86 



BULLETIN 131, UNITED STATES NATIONAL. MUSEUM 



mine 



LEMHI COUNTY 



Argentite has been noted in small amounts in the Pittsburg-Idaho 



50 



OWYHEE COUNTY 



In Owyhee County argentite is a very common ore mineral in the 

 Silver City and De Lamar districts where it occurs in the Black 

 Jack, Trade Dollar, and numerous other mines usually as finely dis- 

 seminated grains in quartz. It often forms crusts surrounding frag- 



2 3 



Figs. 2-3.-2, Argentite. Elongated dodecahedral crystal. 3, Argentite. Distorted crystal 

 simulating orthorhombic symmetry 



ments of granite included in the veins (pi. 1) and the argentite layers 

 are frequently surmounted by a comb of quartz crystals (pi. 4, 

 lower). In the Poorman mine argentite was nowhere very abun- 

 dant but it occurred occasionally as rich streaks of finely disseminated 

 grains in quartz (Cat. No. 14799, U. S. N. M.). In the De Lamar 

 mine this mineral was almost universally present in the silver ores 

 as fine aggregates in quartz or as thin sheets on the walls of narrow 

 veins. It also occurred commonly as nodular or rounded masses 

 inclosed in white clay and ranging in size from small shot to some 

 which were as large as an egg. 57 In the War Eagle mine argentite? 

 finely disseminated in minute grains, constituted rich black streaks 

 in dense quartz containing cavities lined with valencianite crystals 



« J. B. Umpleby. U. S. Geol. Survey Bull. 528, p. 75, 1913. 



" Waldemar Lindgren. Gold and silver veins in Idaho. U. S. Geol. Survey, 20th Ann. Rept., pt. 3, 

 p. 168, 1900. Some of these nodules of so-called argentite have since been found to be naumannite. 



