THE MINERALS OF IDAHO 65 



native gold^as pale yellow flakes and hackly grains associated with 

 bornite in quartz. , } 



,The Eldorado (Geertson) district contains the Eldorado and 

 Ranger as the principal veins. These are brecciated zones with 

 lenses of quartz containing native gold with pyrite, chalcopyrite, 

 and rarely a little galena with their oxidation products. The placer 

 of Bohannon Bar was early worked by Chinese. The first 18 inches 

 above bedrock is the most productive. The gold, which occurs as 

 coarse flakes, fine grains, and small nuggets, is worth $18.60 an 

 ounce. The total production is about $350,000, the annual produc- 

 tion around 1910 being $15,000 to $20,000. 



In the Eureka district the U. P. & Burlington, Queen of the Hills, 

 and Tenday mines are coarse quartz veins in granite. The primary 

 ore contains sulphides, chiefly pyrite with some chalcopyrite and 

 rare galena in isolated grains, irregular bunches, and in some places 

 in parallel bands. The gold is associated with the pyrite. The 

 workings are entirely in the oxidized zone and primary ore is seldom 

 found. The total production of the district is only about $150,000. 



The Forney or Gravel Range district contains gold in veins of 

 crustified quartz in rhyolite. The gold is very finely divided and 

 distributed along dark bands in the ore which react for selenium. 

 The original quartz is hard and flinty but it weathers to a sugary 

 mass. The Monument, which is the principal mine, has a strong 

 vein, while the Rabbitfoot has encountered only stringers of rich ore. 

 The total production of the district is about $100,000. A few small 

 placers have been worked by Chinamen. 



The McDevitt district contains only one important gold mine, 

 which is known as the Copper Queen and has a production of $100,000. 

 The gangue is quartz with a little calcite, and the vein varies from a 

 few centimeters to 3 meters in width. The gold occurs free in small 

 grains associated with bornite and a little chalcopyrite and chalcocite. 



The Gibbonsville district is credited with a gold production of 

 $2,000,000, half of which is from the A. D. & M. mine. Other im- 

 portant mines are the Clara Morris and Twin Brothers, while a 

 number of lesser lodes have been opened. The primary ore consists 

 of auriferous pyritic quartz, 60 per cent of the gold being inclosed in 

 pyrite. The oxidized ore is heavily stained by iron and manganese 

 oxides. 



The Indian Creek or Ulysses district has produced gold to the value 

 of $600,000, mainly from the Ulysses and Kittie Burton mines. The 

 ore bodies are tabular, flat lying quartz veins which are largely 

 oxidized. Some sulphides occur locally. 



The Kirtlcy Creek district contains the White Horse mine as its 

 principal lode-gold deposit. The vein is irregular, with a filling of 

 quartz containing native gold in small grains associated with the 

 54347— 26t 6 



