CHAPTER IX. 



ECONOMICAL GEOLOGY. 



The greater portio"n of our district, with the exception of the area 

 along Eagle Kiver, lying within the limits of the Ute reservation, of 

 course no mining operations can lawfully be carried on. Indeed, the 

 areas in which mineral-deposits are found are limited to the group of 

 mountains in the southeastern part of the district, and to the gneissic 

 rocks about the head of the Eagle. The remainder of the country is 

 covered with sedimentary rocks, mostly of Cretaceous and Tertiary age, 

 in which mineral-deposits are rare. Lignite is found, but, with the ex- 

 ception of that near station 34, it is of poor quality. 



GOLD. 



On Eagle River we met a party of prospectors who claimed to have 

 found gold in placer diggings in paying quantities on some of the 

 streams flowing into the Eagle from the south, below the moutli of the 

 Piney, and above the second caiion. 



On the Korth Fork of the Gunnison, southwest of station 26, we met 

 another party, who said they tried the dirt, and that the colors were 

 good. 



SILVER AND LEAD. 



The Elk Mountain mining district was described in the report for 

 1873. The ores are mainly silver- bearing galena. There are doubtless 

 numerous lodes similar to them at various points around the heads of 

 Slate River and Rock Creek. We did not have time to make a detailed 

 survey here. The rocks are penetrated in all directions by dikes. At 

 the head of " Oh be Joyful " Creek, east of station 32, Mr. Holmes got 

 a specimen of galena associated with i)yrites. On the other branches 

 ledges would probably be found on searching for them, as the rocks are 

 similar. 



COAL. 



Lignite is found at several points in our district. At the mouth of the 

 Gunnison, and in the bluffs on the river from the mouth to the mouth of 

 Roubideau's Creek, it is seen, but of poor quality. This lignite is of 

 Cretaceous age, being found in the sandstones of the Dakota group. 



On Coal Creek, a branch of Anthracite Creek, a bituminous lignite is 

 found in sandstones, which I have referred to the Upper Cretaceous. 

 Two specimens from this creek were examined, with the following 

 results : 



Analysis. 



Specimen Specimea 

 Ko. 1. No. 2. 



Water 5.04 ^ of? a-? 



Volatile matters 3L46 5 "^^ "* 



Carbon , 59.50 139.68 



Ash 5.00 4.30 



100.00 100.00 



This coal is black (brownish -black in powder), has a dull luster, and 

 au irregular fracture. The ash is of a light-reddish color. The analyses 



175 



