110 SURVEY OF COLORADO AND NEW MEXICO. 



a little valley separating the cretaceous and tertiary, occur, in order, clay, 

 sandstone, clay, coal, (one and a bait' to two feet thick,) clay, sandstone. 

 Throughout the beds overlying- this coal seam, in the natural order of 

 deposition, but, in point of fact, underlying it on account of the abnor- 

 mal dip of the rocks, are many indications of lesser coal beds which as 

 yet have not been opened. About ten feet below the nethermost sand- 

 stone (in age above it) occurs a vein of iine brick clay ten to fifteen feet 

 thick. The limit of this stratum on its east side has not yet been reached, 

 but the clay grows purer and more and more free from iron in that 

 direction. On the west side of this bed the clay is not utilizable on 

 account of the presence in it of iron, which forms a fusible double silicate 

 and melts out, leaving the mass full of holes. A pottery has been started 

 and bids fair to compete successfully with the best establishments of 

 similar character elsewhere. As yet the proprietor confines himself to 

 the manufacture of earthenware, but contemplates increasing the extent 

 and variety of the products of this pioneer pottery, and even hopes in 

 time to be able to rival the best English white ware. 



Friday, Jiihj 16. — From Golden City to a j)oint on the mail road nine 

 miles east of Idaho City. — At Mount Vernon the road enters a canon, and 

 after cutting across a red syenite, passes into a region of finely lami- 

 nated gneiss. From this point the springs become more frequent. A 

 number of quartz veins crop out on the sides of the road. Visited a 

 lode situated about two hundred yards south of the road and half a mile 

 Avest of the stage station. The crevice was eight feet wide, and the dis- 

 covery shaft ten feet deep. The quartz (which was very rotten) exhib- 

 ited iron and arsenical pj^ites, copper glance, and galena. The wall 

 rock on the south side was not much weathered, whereas the proper 

 north wall-rock had not been reached. Not far from this opening wa:s 

 another shaft thirty feet deep. The ore from it was rich in malachite, 

 copper pyrites, peacock ore, and copper glance. Beautiful rhombohedra 

 of calcite were obtained from the gangue rock. This claim was to have 

 been sokl in 18G3 to parties in ISTew York for $25,000, but owing to the 

 effect produced by the panic among owners of Colorado mines in that 

 year, the sale was not coiisum mated, and the claim has lain idle ever 

 since. 



An opening on another lode still further west revealed copper pyrites, 

 malachite, galena, and silver glance. Fine calc-spar crystals were ob- 

 tained here also. 



July 17. — Our route lay through Idaho City, nine miles distant. The 

 first i)art of the road wound its way through masses of red and gray 

 gneiss, intersected here and there by veins of white quartz. Now and 

 then this gneiss alters its character, both in habitus and color. Two 

 or three dikes of quartz porphj^ry cross the road. 



The placer mining is carried on extensively on Clear Creek, there being 

 sixteen sluices between the intersection of the road and creek and Idaho 

 City. One party of the miners informed me that they averaged $12 per 

 day per man. They had five rifles in operation. 



On the banks of Clear C^^eek the rocks were much contorted and 

 flexed ; general di^), northwest. 



The hills on the right bank of the creek are much more weathered 

 and rounded off than those on the opposite bank. Gneiss of all 

 kinds, heavy and thin bedded, coarse and fine grained, red and gray, 

 with all possible combinations of these varieties, were observed. Near 

 Idaho the gneiss becomes somewhat suddenly very micaceous. 



There are six sluices in operation between Idaho and three quarters of 

 a mile above that city. Beyond this there is no gulch mining attempted. 



