ransome] DEPOSITS OF RED MOUNTAIN REGION. 219 
In the case of six chimneys occurring on the Yankee Girl, Guston. and Silver 
Bell properties, being the only ones on which depth has been obtained, a marked 
increase in the silver content of the ores occurred irom the surface down to 300 to 
400 feet of depth. 
Changes of character of ore with depth are noticeable in several chimneys, but 
notably so in the Yankee Girl chimney. In this case the distinctive minerals, in 
order of depth, have been galena, gray copper, stromeyerite, and bornite. In those 
chimneys in which enargite has been the surface ore no depth has yet been 
obtained. 
The chimneys frequently change their pitch, sometimes quite suddenly. - * * 
A jump of 15 to 25 feet along some horizontal plane is not infrequent. :: ' * * 
Every chimney is connected with one or two cleavage or fracture planes, which 
bound a portion of the ore body, while on the other sides the ore merges into the 
quartz orandesite. These planes usually show striations. slickensides, and more 
or less gouge material, but are not of great persistence laterally. 
Horizontal planes occur of great strength, which have indirectly had marked 
influence on the ore bodies, changes of character occurring at such horizons. 
In the Guston and Yankee Girl the increase in the amount of the copper ore 
with depth is notable, as is also the fact that the silver is confined mainly to such 
ores. 
Mr. Schwarz supposed the ore to have been broughl in by solutions 
moving chiefly along horizontal planes, perhaps bedding planes, and 
to have been derived from the andesite of the region. His explana- 
tion is essentialty thai of a rather narrowly confined lateral secretion. 
The maximum length of 60 feet was probably exceeded by the ore 
bodies woi'ked in the Yankee Girl and Guston subsequent to 1888. 
One of them is reported by one who saw it to have been 140 feet in 
Length and 20 feet wide. According to Schwarz, several carloads of 
ore from the Yankee Girl carried from L,500 to .'),000 ounces of silver 
per ton, and one lot of about <i tons contained 5,300 ounces of silver 
per ton. Such ores carried 30 to 33 per cent of copper. 
According to Mr. J. Owen, who formerly worked in the Yankee 
Girl and is at present superintendent of the Silver Lake mines, the 
rich bodies of stromeyerite, which had been so productive prior to 
1888, began to change, at about 500 feet in depth, to bornite, which, 
although lower grade, was yet good ore. At this level there was a 
fault encountered which threw the lower portion of the ore body to 
the west. Below this the deposit, according to Owen, has more the 
character of a vein 10 or 12 feet wide and running "north and 
south." It consists, near the bottom of the shaft, of large bodies of 
bornite, with some chalcocite, assaying as much as 57 per cent of cop- 
per. (As pure, nonargentiferous bornite contains only 55.5 per cent 
of copper, this assay, if correct, would indicate the presence of consid- 
erable chalcocite.) Two carloads of this ore were shipped by Owen 
from a winze 40 feet below the bottom of the present shaft, and it is 
said to be abundant at that depth. From the eleventh level ore was 
shipped worth from $500 to $700 per ton in silver and copper. The 
latter averaged about 20 per cent. No large bodies of iron pyrite 
were found in the Yankee Girl, according to Owen. 
