i68 



bordering the shorter arm of the deposit on the northwest 

 and continuing along the larger arm. The siliceous zone 

 is fringed by a band of ore usually from 20 to 25 feet 

 (6 to 7.6 m.) in width and already traced for a distance 

 of nearly 1,400 feet (426 m.). A vertical bore-hole from 

 the main tunnel apparently proves it to a depth of 514 

 feet (157 m.) below that level and it extends to the surface 

 above, a variable distance, depending on the contours 

 of the country but probably averaging about 200 feet 

 (61 m.). The huge tonnage expected from this ore body 

 will undoubtedly be greatly supplemented from other 

 portions of the mineralized area. Workable areas are 

 known to occur at a number of points, but the definition 

 of their extent and quality awaits further exploration. 



The mineralized area at the Hidden Creek mine occurs 

 in a large predominantly argillaceous area surrounded 

 and doubtless underlaid, although at a considerable 

 depth, by granitoid rocks, and cut by dykes and stocks 

 belonging to the same period of igneous intrusion. The 

 argillites were irregularly compressed and folded at the 

 time of the invasion, and the deposit probably occupies 

 an area more than ordinarily crushed and fractured, 

 although this has been masked by subsequent alteration 

 and deposition and is not apparent. A wide, broken 

 zone, rather than a single fissure, is conceived to have 

 afforded the means by which heated siliceous waters 

 carrying iron and copper sulphides in solution ascended 

 from the underlying batholith, altering the argillites in 

 their upward passage and replacing them with silica and 

 sulphides as the pressure and temperature conditions 

 became less severe. 



An origin of this kind would ally the deposit geneti- 

 cally with the loosely defined contact metamorphic group, 

 but the ordinary contact metamorphic minerals including 

 the iron oxides, were not observed and are either absent 

 altogether or are present only in very small quantities. 



