THE MINERALS OF IDAHO 67 



the gold occurs finely disseminated in dark selenium-bearing streaks. 

 The production of the district has been small. 



The Pratt Creek district contains only a single noteworthy gold 

 mine, the Goldstone. The ore consists of quartz in which the gold 

 occurs either in auriferous chalcopyrite or in its alteration products. 



The Texas Creek or Gilmore district is predominantly a lead-silver 

 district. One gold vein is known, however, the Martha vein, which 

 is inclosed in limestone. The ore is largely oxidized and contains fine 

 leaf and flake gold imbedded in limonite. The vein is the property 

 of the Allie Mining Co., and the specimens have been distributed 

 somewhat, in collections, the locality being given as the Allie mine. 



The Yellowjacket district has a lode production of $450,000. The 

 ores are fissure fillings and replacements. The gangue is coarse 

 white quartz. Pyrite carries most of the gold, although in the 

 Columbia mine the gold is contained in chalcopyrite. Some small 

 placers have been worked. 



ONEIDA COUNTY 



The Cariboo mine in the Cariboo district contains massive aurifer- 

 ous chalcopyrite and arsenopyrite, or auriferous malachite and chryso- 

 colla, or spongy limonite formed by oxidation. 10 



OWYHEE COUNTY 



The Carson (War Eagle, Silver City, Florida Mountain) district 

 contains a large number of rich veins which have made a very great 

 production, the total production of the county, including the De 

 Lamar and Mammoth districts, from earliest discoveries to the end 

 of 1898 in precious metals amounting to a value of $27,963,652. The 

 ratio of value between gold and silver in the production previous to 

 1880 is not known. From 1880 to 1898 the production was gold 

 $6,477,065 and silver $S,0S0,065. The silver is generally predomi- 

 nant in value as well as in weight but the ratio between the two metals 

 varies abruptly from year to year and from mine to mine. Native 

 gold is of universal occurrence associated with native silver and 

 various sulphides and sulpho salts of silver, but is most abundant in 

 oxidized ore. This gold is normally very pale yellow in color, repre- 

 senting the high-silver alloy known as electrum. The veins are of 

 post-Miocene age in granite, rhyolite, or basalt. They arc normal 

 fissure veins in which the ore mostly occurs as a typical filling of 

 cavities, although some low-grade ores in rhyolite are formed by re- 

 placement of country rock. The principal ore minerals are finely 

 divided argentite and chalcopyrite, the latter being highly auriferous. 

 The gangue consists of quartz and valencianite (orthoclase). The 

 ratio of gold to silver varies even in the same mine, some very rich 

 bodies of gold ore being found in predominantly silver mines and 



» Specimens Cat. No. 51869-51870, U.S.N.M. 



