8o 



to 274 m.) wide, and from 40 to 125 feet (12 to 38 m.) 

 thick. The eastern lens is apparently shorter but 

 approaches the magnitude of the other in width and thick- 

 ness. The general strike along the outcrop is about N. 10° 

 E. with dips to the east ranging from 45 to 60 degrees. The 

 dip flattens with depth and on the lower levels averages 

 from 15 to 30 degrees. The general pitch of the ore bodies 

 is about 18 degrees to the northeast. The vertical range 

 from the south end of the main "glory hole" to the lowest 

 working levels is 675 feet (206 m.). The structural foot- 

 wall is the jasperoid zone of the Brooklyn formation, and 

 in places, the siliceous rocks of the Knob Hill group. The 

 hanging wall is a purely commercial one and the ore either 

 grades insensibly into barren gangue or terminates sharply 

 against a gouge-filled fissure. The ore bodies and adjacent 

 rocks are traversed by an intricate system of fissures 

 which run in all directions and dip at all angles. They 

 have had a most important influence on ore deposition 

 as they formed channels for the ore-bearing solutions 

 which permitted a uniform distribution of their metallic 

 contents. In many cases the ore adjacent to these fissures 

 is of noticeably higher grade. Some of the fissures have 

 been subsequently filled with banded quartz, calcite and 

 chalcopyrite. 



The only displacement noted is along one of the major 

 fissures which faulted the ore body with a throw varying 

 from zero to 120 feet (36 m.) along a dip of 55 degrees 

 to the west. (See section). 



The ore is mainly massive with local banded areas. 

 It consists of chalcopyrite, which with pyrite and hematite 

 is finely and uniformly distributed through a gangue 

 composed almost exclusively of garnet, epidote, quartz, 

 calcite and chlorite. The pyrite occurs in grains, crystals 

 and streaks, while the hematite (specularite) occurs in 

 platy aggregates. Magnetite occurs in masses and irre- 

 gular lenses at intervals through the ore bodies but it is 

 relatively unimportant. The average content of the ore 

 is: copper 1-25 per cent; gold 0-04 ounces and silver 0-3 

 ounce per ton. Along the outcrop the ore has been 

 leached out in part but has produced no noticeable second- 

 ary enrichment at lower levels. 



The zone of contact metamorphism and the develop- 

 ment of lime-silicates is believed to have been the result 

 of metasomatic replacement of limestone by solutions 



