230 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



BONNER COUNTY 



Coarse manganiferous buff siderite forms the gangue of tetrahedrite 

 and pyrite in ores from the Little Joe or Keystone mine at Talache 

 near Blacktail Mountain on the west shore of Lake Pend d'Oreille. 



CUSTER COUNTY 



In the Alder Creek (Mackay) district siderite is said to be the 

 gangue mineral in a lead-bearing vein opened from the Darlington 

 shaft on the Empire Group. 42 In the Bay Horse district siderite is 

 the characteristic gangue mineral of the silver-copper ores, the chief 

 valuable mineral of which is argentiferous tetrahedrite. The princi- 

 pal deposits of this type are the Ramshorn and Skylark mines with 

 numerous veins of lesser importance, notably the New Silver Bell, 

 one of the Hoosier veins, and some small deposits near the head of 

 Garden Creek. 43 Typical specimens of the ore from the Utah Boy 

 No. 5 tunnel of the Ramshorn mine show fresh clean coarsely crystal- 

 line translucent buff siderite as the gangue of massive tetrahedrite. 

 Small vugs contain minute crystals of siderite, arsenopyrite, and 

 tetrahedrite coated with mossy chalcopyrite. In the Bay Horse 

 district siderite also occurs as the gangue of galena in lead-silver 

 mines, including the Red Bird, Excelsior, Beardsley, Riverview, 

 Pacific, and Cinnabar mines. These ores are now largely oxidized. 44 

 Siderite also forms the gangue of galena in the Ella group on Kinni- 

 kinnick Canyon. 



In the Loon Creek district siderite occurs as the gangue of galena 

 in the Lost Eagle, Metcalf, and other mines. The principal occur- 

 rence of the iron carbonate in this district, however, is as the gangue of 

 auriferous chalcopyrite in the copper-gold deposits of which the 

 Lost Packer mine is the most important example. In this mine there 

 are 3 principal ore shoots in the south one of which siderite is the 

 predominating gangue mineral. 45 The siderite is coarsely granular 

 and pale buff in color. 



FREMONT COUNTY 



A specimen of ore from the 125 foot level of the Old Scott mine of 

 the Birch Creek Mining Co., Kaufman district, consists of galena in 

 granular buff siderite. 



LEMHI COUNTY 



In Lemhi County siderite has probably been the important gangue 

 mineral of the lead-silver ores, but in the ores now mined it has been 

 largely destroyed by oxidation. Specimens have also been reported 



« J. B. Umpleby. U. S. Qeol. Survey, Prof. Paper 97, p. 54, 1917. 



« J. B. Umpleby. U. S. Oeol. Survey, Bull. 539, pp. 31-33, 1913. 



« J. B. Umpleby. U. S. Qeol. Survey, Bull. 539, pp. 38-39, 1913. 



«« J. B. Umpleby. U. S. Qeol. Survey, Bull. 539, pp. 94-95, 1913. 



