68 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [hull. 213. 
centers in Pierce, but also extends to the headwaters of Lolo Fork 
on the south and to the North Fork of the Clearwater on the north. 
Character of ore, — The primary deposits are almost exclusively 
fissure veins, and with them are associated extensive placers of an 
age ranging from Neocene to Recent. In the northern Bitter root 
Mountains and on Lolo Fork veins occurring in pre-Cambrian (?) 
schists contain chiefly copper, lead, and silver, although some gold is 
also found on Lolo Fork. The Curlew mine, at the eastern foot of 
the Bitterroot Mountains, contains argentiferous galena, and is located 
on a fissure with limestone (pre-Cambrian?) as the foot wall and, 
according to accounts. Pleistocene valley gravels as a hanging wall. 
The mine is not worked at the present time. On the Upper Bitter- 
root River veins cutting porphyry likewise carry chiefly copper and 
silver, while argentiferous galena is also known from the Monitor 
mine, worked on a vein in gneiss on the divide between the Bitter- 
root and Salmon livers. Gold-bearing gravels have been mined for 
many years on Hughe Creek. Southward this belt connects with the 
gold-bearing deposits at Gibbonsville and Shoup. The rocks at Hughe 
Creek and Gibbonsville are pre-Cambrian (?) quartzites and slates. 
West of these districts extends a wide granite area which, as far as 
known, is barren of mineral deposits. There can be no doubt that 
the Clearwater drainage was very thoroughly prospected for placers 
during the early days of mining, but outside of the South Fork very 
little of value lias been found. In the upper part of the mountains 
the glaciation would naturally have swept away any placer deposits 
which may have existed, and in this denuded portion it is not impos- 
sible thai veins may be found. Nothing of much value lias yet been 
encountered. A large vein containing silver is reported to occur on 
Rhodes Peak north of the Lolo trail. Along t he Salmon River the 
conditions are probably more favorable, and prospecting in the iso- 
lated region between Dixie and Shoup might develop something of 
value. 
As stated before, the western belt contains chiefly gold; only a few 
scattered copper deposits are known. The placers of Elk City and 
Florence are well known in the history of Idaho and are still worked 
to some extent. Veins which furnish the material for these placers 
are known to occur in all these localities. The principal mining dis- 
tricts are those of Florence, Dixie, Elk City, and Newsome Creek. 
The veins, occurring chiefly in gneiss, are almost exclusively of quart! 
zose character and contain from 1 to 10 per cent of sulphurets, besides 
more or less native gold. The Buffalo Hump district, discovered in 
1898, is situated on the high divide between the Clearwater and the 
Salmon. It contains many strong quartz veins in granite and slate, 
with a varying percentage of free gold and auriferous sulphides. 
Active work is in progress there at the present time. The north- 
western mineral-bearing area contains placers along Lolo Fork, 
