BIG PITTSBURGH MINE. 483 



Westward from the shaft, a drift runs through White Porphyry, which 

 connects with the McCormick shaft of the Big Pittsburgh, on the dividing 

 line between the two claims. This shaft was sunk by Mr. Tingley S. 

 Wood, superintendent, after explorations in the southern portion of the claim 

 had proved fruitless, with the idea that a portion of the Matchless body 

 might be found within the Pittsburgh lines. His expectations were real- 

 ized, and a narrow strip of very rich ore was found north of the dike, and 

 directly under the Wash, being, as the map shows, the extreme southern or 

 lower edge of the Blue Limestone outcrop. From this shaft two cross-cuts 

 were run northward across the porphyry dike toward the north line of the 

 claim, and an up-raise made along that line disclosed the ore body above 

 the White Porphyry or Parting Quartzite, as the case might be. Up-raises 

 were also made in the porphyry dike, which showed that it extended up to 

 the Wash, or, in other words, outcropped. Owing to a surveyor's error the 

 line drift was run on the Matchless side of the boundary line; but, the error 

 being discovered, the Matchless was reimbursed for the ore taken from its 

 ground. What is known about the balance of the ground owned by the Big 

 Pittsburgh Company will be given below in the description of the southern 

 portion of the map. 



Robert E. Lee. This claim, in spite of its small area, has been among 

 the greatest silver producers in the district. It has been owned by differ- 

 ent individuals, and for various reasons it has not been possible to obtain 

 very trustworthy figures with regard to the actual value of its product. 

 The ore has been remarkable for its high tenor in silver f.nd its freedom 

 from lead. It is also very silicious and contains a relatively small percent- 

 age of iron, for which reason it is by itself not so well adapted for smelting 

 aa the average ore of the district, and a great deal of the low-grade ore 

 from the mine has been reduced by amalgamation. The ore horizon is here 

 directly overlaid by a body of Gray Porphyry, whose thickness could not 

 be ascertained. It is evidently of limited extent, as it was not cut by the 

 shafts of the adjoining claims. It may be an offshoot from the dike, or, as 

 indicated on the map, simply a small intrusive sheet. In the western por- 

 tion of the claim this porphyry-covering, together with the normal sheet, 

 of White Porphyry and the main Gray Porphyry sheet above that, has 



