66 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



products formed by oxidation of primary pyrite, chalcopyrite, and 

 galena. Gold-bearing placers occur along Kirtley Creek in the recent 

 stream gravels. At the upper end of the deposit the gold is confined 

 to the bedrock but toward the lower end it is scattered throughout 

 the bottom 2 or 3 meters. It grades from the size of shot above to 

 small flakes below, nuggets up to 75 cents in value being found only 

 rarely. 



The Leesburg district is credited with a placer production of 

 $5,000,000 and a lode production of $225,000. The placer deposits 

 in the Leesburg Basin cover 1,000 acres. The gold, most of which is 

 confined to the first 40 centimeters above bedrock, is in coarse and 

 fin,e grains with rare nuggets worth $15 to $20. The district, which 

 was discovered in 1866, saw its greatest production in the first four 

 years of its history. The population at that time was 7,000 and 

 freight had to be brought by team from Fort Benton, Mont. 



The Mackinaw district contains the Moose Creek placers, which 

 cover 200 acres and have produced placer gold to the value of about 

 $1,000,000. The gold, which is worth $19 an ounce, occurs in cracks 

 in the bedrock, or up to 40 centimeters above bedrock, beneath the 

 gravels 3 to 5 meters deep. The Beaver Creek placers have yielded 

 $100,000. Lode-gold deposits of various types occur: (a) Quartz 

 veins accompanied by stockworks in granite, including the Italian 

 mine and adjacent properties, with a production of $175,000; the 

 gold is accompanied by pyrite, sphalerite, and galena, (b) Replace- 

 ment auriferous pyrite-quartz lodes along faults between contact 

 metamorphic sediments and granite; to this class belong the Gold 

 Dust, Gold Reef, and Gold Flint mines, (c) Replacement along shear 

 zones in schist by pyritic quartz accompanied by development of 

 epidote and magnetite as in the Mayflower and Copper King veins. 

 (d) Small auriferous quartz lenses in schist and in granite, including 

 the Shoo Fly vein; these lenses are the source of the Moose Creek 

 placer gold, (e) Coarse bluish quartz containing gold with auriferous 

 chalcopyrite and sphalerite at the contact of a biotite-monzonite 

 dike. 



The Mineral Hill or Shoup district has a recorded gold production 

 of $750,000, all of which is from lodes which are coarse quartz veins 

 containing sulphides irregularly distributed. The sulphides, which 

 include pyrite with less galena and sphalerite, are auriferous. Oxida- 

 tion extends only to shallow depths. The principal mines are chiefly 

 the Monotech, which has produced $175,000; the Grunter, which 

 produced $50,000 from ores near the surface; the Kentuck, Clipper 

 Bullion, and Big Lead. Some small streaks of the ore are very rich. 



The Parker Mountain district is similar to the Gravel Range dis- 

 trict in that its veins are of late Tertiary age and are inclosed in 

 Tertiary lavas. The gangue is quartz which contains adularia, and 



