482 GEOLOGY AXD MINING INDUSTRY OF LEADVILLE. 



very thick, reaching 30 feet in places, and is extremely rich. This ore 

 differs from any hitherto observed on Fryer Hill in that it is almost entirely 

 free from lead. Its silver exists as line particles and films of chloride or 

 chloro-bromide, disseminated through an ocheroiis sandy mass, and some- 

 times coating- the cracks and cleavage faces of the chert. Another differ- 

 ence between this ore Ijody and those of the portion of the hill already 

 described is the small amount of manganese found, and the condition of 

 the iron oxide, which is here more generally anhydrous, whereas in other 

 parts of the region it is always hydrated or in the form of limonite. 



Hibernia and Big Pittsburgh. ThcSC tWO claimS wiU bc dcSCribcd together, 



as the only portion of them yet found productive is the extreme northern 

 edge, where the western continuation of the Lee ore body extends a short 

 distance across their lines. The Gray Porphyry dike is here about thirty 

 feet wide and very well defined, cutting across the Blue Limestone horizon 

 into the underlying White Porphyry; and pay ore has thus far been con- 

 fined mainly to its northern flanks, though, as will be shown later, there is. 

 good evidence for assuming that the continuation of the southern ore shoot, 

 as developed in the ground to the westward already described, once existed 

 here also, and that it should be sought for further east, where the ore hori- 

 zon has not been removed by erosion. 



The Hibernia shaft, which was sunk just south of the dike, passed 

 through 100 feet of Wash into soft black iron, with chert at the base and a 

 little pay ore, having a total thickness of about twenty-five feet. Drifts 

 run northward from the shaft across the dike to connect with the stopes in. 

 the little triangular or wedge-shaped point of the claim beyond. These 

 stopes were five sets of timber high, and the little triangular area was an 

 almost solid mass of rich ore: near the top was a layer of chert extending 

 from the Lee ground, which was there supposed to be the top of the ore 

 body; it was here broken through and the ore found to extend up to the 

 Wash. The quartzite floor dips northward into the Matchless ground. 

 Southward from the shaft a prospecting drift runs over two hundred feet 

 in the underlying White Porphyry, striking the Parting Quartzite at the 

 end. A cross-cut to the eastward from this drift finds barren iron resting 

 on the White Porphyry, and a winze sunk in the floor of the drift is said to- 

 have found White Limestone. 



