THE MINERALS OF IDAHO 



265 



CUSTER COUNTY 



Azurite accompanies malachite in the oxidized ores of the Alder 

 Creek district. It is not an abundant mineral in the deposits, but is 

 very generally present in the different stopes. Locally it is well 

 crystallized in tabular crystals. 79 Else- 

 where in the county this mineral appears in 

 the oxidized portions of the veins, but is 

 nowhere abundant enough to constitute an 

 ore. In the Bayhorse district it occurs 

 generally in small cavities in partly oxidized 

 tetrahedrite ore. Minute crystals incrust 

 tetrahedrite and chalcopyrite in specimens 

 from the Bull of the Woods mine (Cat. 

 No. 56518, U.S.N.M.) and thin coatings 

 occur with malachite and bindheimite in 

 partly oxidized galena-tetrahedrite ore from 

 the Ramshorn mine (Cat. No. 51863, 

 U.S.N.M.). A specimen from the No. 3 

 tunnel, Silver Bell mine, Bayhorse district, 

 shows thin botryoidal coatings and drusy 

 crusts and seams of azurite with oxidizing 

 tetrahedrite. Small crystals in spongy lim- 

 onite surrounding tetrahedrite in ore from 

 the Skylark mine were measured and are 

 illustrated in the drawing, Figure 71. These 

 gave the following measurements: 



Fig. 71.— Azurite. Skylark Mine, 

 Bayhorse district, Custer 

 County 



M casurements of azurite crystal, Skylark mine 



ELMORE COUNTY 



Small amounts of azurite have been reported as occurring in the 

 ores of the Tahoma mine, Atlanta district. 



LEMHI COUNTY 



Although nowhere as abundant as malachite, azurite has been 

 noted in most of the districts. It occurs in the oxidized portions of 

 those veins which bear copper minerals. 



"JB. Umpleby U ,S .Geol. Survey ,Prof. Paper 97 ,p. 50, 1917 



