352 University of California Publications. [Geology 



the gold ores have not been exploited to any notable extent and 

 the writer has only seen the gossan of one deposit. The gangut; 

 is a silicified limestone more or less stained with ocher from the 

 oxidation of pyrite. The deposit, so far as could be judged from 

 the collar of a prospect pit, is disposed parallel to the stratifica- 

 tion of the Ruth limestone. The writer was informed that the 

 ore ran at $18.00 per ton but can not vouch for the fact. 



This deposit lies in the limestone a little below the porphyry 

 in which the Ruth copper mine is situated. 



The lead-silver deposits to the north of the Ruth are above 

 the porphyry. On the Phoenix claim a considerable amount of 

 development work has been done and the character of the de- 

 posits can to some extent be observed. The ores are for the most 

 part distributed along the planes of bedding in the limestone. 

 The latter is inclined at quite low angles (18° to the N.E.) and 

 mineralization has occurred at different stratigraphic horizons 

 one above another. These successive sheets of ore are connected 

 with one another by a vertical, mineral-filled fissure, and the 

 tabular deposits so connected seem to pinch out at no great dis- 

 tance from the vertical vein. The tabular deposits near the ver- 

 tical vein vary from one to three or four feet in thickness and 

 the vertical vein was at one place observed to be two feet wide; 

 but in both the vertical vein and the tabular deposits parallel 

 to the strata the thickness varies rapidly. The occurrence of 

 the ores in the deposits is, also, so far as could be observed, far 

 from uniform. The prevailing color of the ore in the mass is 

 light ocherous yellow and iron minerals appear never to have 

 been abundantly represented in the deposits. The chief gangue 

 is silica which appears to be a replacement of the limestone and 

 the croppings at the surface resemble closely the quartz blout 

 of the neighboring porphyry. Some of the limestone imme- 

 diately adjacent to the deposits is of a dead white chalky char- 

 acter and is somewhat slickensided. It resembles massive kaolin 

 but effervesces freely with acid. The siliceous vein matter car- 

 ries galena, a sample of which was examined by Mr. Ross and 

 found to contain 22.4 ounces of silver to the ton and $1.49 in 

 gold. Besides the galena there are azurite, malachite, and chrys- 

 ocolla in sparing quantities, a little cerussite and considerable 



