92 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



This description of galena from the Minnie Moore also applies to 

 the mineral from other mines of the district. The galena, always the 

 most prominent mineral, is often coarsely granular with parallel 

 orientation over large areas, though the very fine grained dense 

 variety known as steel galena occasionally occurs. The twin stria- 

 tion described above is almost universally present in all veins; and 

 this gives the mineral a peculiar fibrous appearance, the striation 

 being parallel to the walls of the vein and doubtless being every- 

 where due to pressure. In many places galena is almost the only ore 

 mineral and is associated with a little siderite or intermediate carbon- 

 ates which frequently form a lining about the bodies of galena. 

 Banding indicating filled cavities appears in the smaller veins. Ore 

 from the Democrat vein in granite is banded and shows quartz, 

 calcite, galena, and tetrahedrite deposited in the order named. The 

 galena was twinned by the same movement which shattered the 

 tetrahedrite. Second-grade ore may consist of a network of seams of 

 siderite or intermediate carbonates cutting black calcareous shale. 

 The galena then usually appears as grains in the veinlets; more 

 rarely it lies directly in the sedimentary rocks. In the mines of the 

 Democrat type pyrite, galena, and zinc blende may also occur as 

 abundant grains directly inclosed in the altered granite. Many of 

 the Wood River mines are noted for the heavy bodies of practically 

 pure galena occurring in them. The Minnie Moore in one stope 

 showed 16 feet of solid galena. 62 



In the Rosetta and Warm Springs districts galena occurs in a 

 number of mines. Specimens from the Dollarhide mine show it in a 

 granular form in quartz with sphalerite and arsenopyrite, and ore 

 from the Golden Glow mine consists of granular massive galena in 

 quartzite. The ore of the New Hope (Warfield) property on Warm 

 Springs Creek consists of pure fine grained massive galena with very 

 fine grained sphalerite. 



BOISE COUNTY 



In the Banner district galena is a rare constituent of the rich silver 

 ores of the Banner and adjacent mines. 



In the Deadwood district this mineral in granular masses has been 

 noted in ore from Hall Bros, property, Deadwood Basin. 



In the Highland Valley, Idaho City, and Quartzburg districts 

 galena occurs in the primary gold ores below the oxidized zone as 

 disseminated grains in quartz with pyrite, arsenopyrite, and. more 

 rarely, chalcopyrite, bismuthinite, and galenobismutite. The galena 

 frequently carries gold. 



The occurrence of lead sulphide in the Summit Flat (Pioneerville) 

 district is similar to the last. Ore from the stope below the upper 



« 2 Waldemar Lindgren. U. S. Geol. Survey, 20th Ann. Rept., vol. 3, pp. 214-215. 



