PRINTER BOY HILL. 51 1 



with the ore body of the Florence, but, as followed in depth by a winze, 

 was found to pinch out entirely, furnishing one of many proofs that the ore 

 entered the limestone from above and not from below. 



The dikes of Gray Porphyry on either side of the Florence are thirty 

 to fifty feet wide and can be traced along the hill for considerable distances. 

 They have the characteristic large crystals of orthoclase porphyritically 

 distributed through the mass. 



East of the Florence the Minor tunnel has been run several hundred 

 feet on the contact without finding ore, but good ore is said to have been 

 obtained from the First National mine, still farther east. In the latter the 

 limestone seems to be split into two parts by the cross-cutting zone of White 

 Porphyry. 



To the westward the contact has been developed by the Sangamon 

 tunnel, the Wilson, Brian Boru, G. M. Favorite, and other mines,, and some 

 ore has been shipped, but no certain information was obtained in regard to 

 its quantity or its quality. 



Although some prospects showing ore may have escaped observation, 

 the above descriptions suffice to show that on either side of Iowa gulch in 

 the vicinity of the three dikes of Gray Porphyry the Blue Limestone con- 

 tact is ore-bearing over a comparatively large proportion of its extent. 

 It can, however, hardly be said to have been thoroughly explored as yet, 

 nor are the ore developments as rich or extensive as the geological condi- 

 tions would lead one to expect. It may, therefore, reasonably be assumed 

 that future explorations in this area, if systematically conducted, will prove 

 remunerative. The most promising direction for exploration would seem 

 to be to the northward under Printer Boy Hill. Next to that, the easterly 

 continuation of the contact in depth beyond the First National affords a 

 promising field. It must be borne in mind, however, that in this direction 

 the zone of cross-cutting White Porphyry will soon be reached, where the 

 Blue Limestone will be found split into two wedge-shaped masses, and thus 

 there will be two contacts between limestone and porphyry. 



IOWA GULCH. 



In Iowa gulch, to the westward, the contact is cut off by the Mike fault, 

 after crossing the gulch just beyond the G. M. Favorite. A little farther 



