COLORADO PEINCE MINE. 505 



expert to be a propylite dike. It is, however, only a fine grained 

 conglomerate of rounded pebbles of quartz in a clay matrix. So far as 

 explored, the vein is confined to the horizon of the Lower Quartzite, the 

 upper 20 feet of which are calcareous. It may have extended up into the 

 White Limestone, but it has not yet been followed into the White Porphyry 

 below and shows a tendency to pinch in that direction. The ore is essen- 

 tially a free-gold ore and is generally stained by oxide of iron and carbon- 

 ate of copper. Galena occurs sparingly, having been only observed in a 

 few spots. Carbonate of lead is said to have been found. The first and 

 second class ores are generally sent to the smelting works at Argo, only 

 the third class going to the stamp mill. 



The vein seems to be the result of the action of percolating waters 

 along a fracture plane in the formation, which was very probably formed 

 at the time of the displacement of the Colorado Prince fault, with which it 

 has a general parallelism. The ore is probably the result of the oxidation 

 of pyrites, and whether it was originally concentrated in this form in its 

 present position or brought in as a secondary deposition from the sur- 

 rounding rocks it is difficult to say definitely. 



The general dip of the formations in these workings is steeply to the 

 south, sometimes varying a little to the west and again to the eastward. 

 Its observed angle also varies from 35 to 60 in the Colorado Prince work- 

 ings, the steeper dip occurring near the Miner Boy shaft. The intersections 

 obtained in the Colorado Prince tunnel are shown on the section. The 

 Kentucky or Miner Boy tunnel was run for the following distances through 

 the successive formations: Lower Quartzite, 200 feet; White Limestone, 200 

 feet; White Porphyry, 40 feet; Parting Quartzite, 35 feet; Blue Lime- 

 stone, 50 feet to the bottom of shaft No. 1. These figures, it must be 

 remembered, are not actual thicknesses of the formations. The lower part 

 of the Blue Limestone as exposed in Miner Boy No. 1 shaft is thoroughly 

 impregnated with oxide of iron and is said to have yielded some very good 

 assays. The No. 2 shaft of the Miner Boy found black shales of the Weber 

 Shale formation directly beneath the Wash. 



