504 



GEOLOGY AIN'D MINING 1>'L)LSTKY OF LEADVILLE. 



Fig. 3. 



Miner Bay Tunnel 



Colorado Princ §^;53v>\r 

 Tunnel 



The most important mine of this group is the Colorado Prince, AA'hich 

 has its own stamp mill for ernshing and .amalgamating its ore. According 

 to the reports of experts who have examined it, it has a very large body of 

 rich ore, but the practical results of work do not thus far seem to have 

 justified their prognostications. The management of the mill has Ijeen so 

 frequently changed that it was impossible to learn the actual working results 

 of treatment over a long enough period to determine whether the apparent 

 want of success was due to the quality of the ore itself or to faulty methods 

 of reduction. 



The deposit of the Colorado Prince and }.Iiner Boy mines is somewhat 

 in the nature of a gash vein in the Lower Quartzite. It stands at an average 

 pitch of 75° to the east, varying between 60° and the vertical. Its strike 

 is about N. 15° W. It varies in width from a few inches to five or six feet, 

 and in the upper workings is said to have been stoped out on a width of 

 20 feet. It has no distinct walls or clay selvages, and the matrix of the 

 ore is principallv decomposed quartzite, more or less stained by iron oxides. 

 Near the Miner Boy No. 3 shaft it splits into two branches, one following 

 its general direction, the other being more nearly north and south. Fol- 

 lowing the vein is a thickness of one to three feet of light-colored de- 

 composed rock, called by the miners trachyte and considered by one 



