GOLD ORES. 1173 



of these rich deposits appeared upon an average at least 120 meters below 

 ground- water level. Mr. Moore" states that the depths of the deepest shafts 

 in the Cripple Creek district vary from 240 to 450 meters. On Battle 

 Mountain are the Portland, Granite, Burns, Ajax, Stratton's Independence, 

 Strong, Gold Coin, and Modoc. At Bull Hill are the Last Dollar, Blue Bird, 

 Logan, American Eagles, Wild Horse, Isabella. At East Spur Bull Hill 

 are the Independence T. & M. Co., A^indicator, Lillie, and Golden Cycle. 

 He says in reference to these deposits: "All but one of these shafts have 

 good bodies of ore and excellent indications for the future at the lowest 

 levels to which they have thus far attained. Certain of these shafts, to wit, 

 the Last Dollar and Blue Bird, show some of the richest ore ever mined in 

 the district at their lowest levels." Mr. Moore regards these deep, rich 

 deposits as due to the secondary action of descending waters. It has 

 already been noted that in the Cripple Creek districts the values in the 

 upper part of the veins near the ground-water level are very largely in 

 native gold; deeper they are largely in the tellurides, the sulphides being 

 comparatively poor; while still deeper they are to a large extent in the 

 sulphides. 



If these are facts they seem to be evidence that the ores of the Cripple 

 Creek district have undergone two concentrations. The first concentra- 

 tion was by ascending waters, and the ores were originally deposited in 

 some measure as tellurides, but perhaps more largely as free gold associ- 

 ated with sulphides. In consequence of later denudation, with action by 

 descending waters, secondary segregation may have taken place and pro- 

 duced two rich upper horizons, that of free gold largely above the level of 

 ground water and that of the rich tellurides and associated free gold, mostly 

 below it. 



Exceptionally the Cripple Creek mines have a deep horizon of rich 

 tellurides. In most districts where rich ores occur at some depth below 

 the level of ground water the reduction of the gold to its free state is 

 believed to be largely the work of the base sulphides. As already noted, 

 in the deeper workings of the Cripple Creek district the values are largely 

 in the sulphides, and the tellurides are subordinate. The natural explana- 

 tion of the rich tellurides is that as the original sulphides and tellurides 

 rose above the level of ground water the gold and tellurium were both 



a The Cripple Creek Times, December,. 1902. 



