167 



some of the ground overlying the lean portion being well 

 mineralized with sulphides. 



Pyrrhotite, while much less abundant than pyrite, 

 is common throughout the greater part of the mineralized 

 area. It occurs intermingled with the pyrite, and also 

 forming comparatively large masses usually specked with 

 chalcopyrite. 



Chalcopyrite in grains, small aggregates of grains, 

 and in thin layers usually accompanies the iron sulphides 

 where the replacement is complete or nearly so, and also 

 occurs in small quantities scattered through portions of 

 the schistose areas. The proportion present, while var- 

 iable, is always small and in certain areas seems to be 

 absent altogether. The chalcopyrite is associated so 

 intimately with the iron sulphides that there is little doubt 

 that both are the products of the same period of deposi- 

 tion. 



Bornite was found at one point, but only as a surface 

 alteration mineral, and it does not occur so far as known 

 as a primary mineral of the deposit. 



Among the non-metallic minerals, quartz is the 

 most prominent. A wide siliceous zone crosses and bounds 

 portions of the mineralized area, and the large sulphide areas 

 are all more or less siliceous. Calcite occurs occasionally 

 but is not prominent. Portions of the area included in 

 the mineralized zone on the accompanying map consist 

 of greenish micaceous schists often highly siliceous. These 

 carry significant quantities of sulphides in some places 

 and are nearly barren in others. 



The iron sulphides in the Hidden Creek mine carry 

 very low values in the precious metals and the commercial 

 value of the deposit depends mainly on the copper content. 

 Chalcopyrite usually accompanies the iron sulphides, 

 but in variable amounts. Some areas are nearly barren, 

 while others contain sufficient quantities to constitute 

 a low grade, and over limited areas a medium, grade copper 

 ore. 



EXTENT AND ORIGIN OF THE ORE BODIES. 



The most important body of commercial ore so far 

 outlined in the boring operations of the Company, occurs 

 southeast of the siliceous zone previously described as 



