474 GEOLOGY AND MIXING INDUSTRY OF LEADVILLE. 



White Limestone, with its characteristic white chert segregations, but no ore. 

 It was intended at time of visit to continue it still farther, as soon as a Corn- 

 ish pump could be put in to control the great influx of water, which is 

 almost invariably found when a certain depth is reached. Although there 

 is no geological impossibility of the occurrence of ore in depth, the facts of 

 observation are so unanimously adverse to its probability that this may be 

 said to be a misdirected expense of labor and money, and one which, if 

 devoted to the exploration of the Blue Limestone horizon in any of its 

 various subdivisions, would be far more likely to yield practical results. 



The main ore horizon north of the dike has a general dip to the north- 

 east, although, as defined by its general contact with the underlying por- 

 phyry, it incHnes locally to the northwest near the Climax boundary. The 

 main dip of the formation is, however, to the north, and, as in the previously 

 described mines, this dip steepens rapidly in the northern part of the claim, 

 though the gentle dip continues some distance north of the main hodj. The 

 first lower sheet of porphyry, as developed by the drift driven from No. 1 

 shaft to connect with No. 3, is remarkably full of chert fragments, most of 

 which appeal- to have been simply caught up in the porphyry flow ; some, 

 on the other hand, are apparently segregations in the mass of the porphyry 

 since its consolidation. 



The principal ore body occurs along the north flank of the dike, in 

 some cases being seen to wedge out between this and the overlying White 

 Porphyry. It is very variable in thickness ; thus at No. 2 shaft the whole 

 horizon is only 10 feet thick; at 70 feet to the southward it has thickened 

 to nearly 50 feet, of which the upper 30 feet are in pay ore, mostly rich 

 sand carbonates. A similar large body of sand carbonate, 20 feet in thick- 

 ness, was found above the main level east of No. 1 shaft, which was 45 feet 

 in length. As already mentioned, most of these bodies are in the upper 

 part of the ore horizon; rich ore also occurs irregularly in different parts 

 of the horizon and also in the lower ore sheets, though the latter contain as 

 a rule a smaller proportion of pay ore. Explorations to the northward, as 

 far as conducted, find a large proportion of barren ground in the ore hori- 

 zon, and, as elsewhere, the influx of water as the formation descends ren- 

 ders exploration difficult and expensive. Several small ore bodies liave, 



