97 



has been subjected, there is little of the hanging wall of the 

 sill left in the productive area at Cobalt. But of the veins 

 thus far worked the two or three that occur in the hang- 

 ing wall are productive to the greatest depth reached in the 

 area. 



In the foot wall of the sill, or what was the foot wall 

 before erosion took place, the rich or merchantable ore is 

 limited as to the depth to which it extends. This depth 

 below the sill is variable, depending on the character and 

 strength of the fissures, and other factors already mentioned. 

 Rich ore descends to a less depth in narrow more irregular 

 fissures than in wide ones. 



As has been said previously, much the greater part of 

 the ore has come from veins in the fragmental rocks of the 

 Cobalt series in the foot-wall of the sill. These veins, on 

 reaching the contact of the Cobalt series with the underlying 

 Keewatin, either end at the contact, or split into stringers, 

 or continue down into the Keewatin. In many cases the 

 rich ore disappears when the veins penetrate the Keewatin. 

 On the other hand, a few veins in stronger fissures have 

 been found to be productive in the Keewatin, that, before 

 erosion, lay beneath the sill. 



In the veins both in the diabase and Keewatin rocks, ore 

 is found to occur more irregularly distributed than in those 

 of the Cobalt series. In other words, it tends to occur in 

 bunches. 



The best veins that have been worked in the diabase are 

 one on the Kerr lake property and one on the O'Brien. Of 

 those in the foot-wall of the sill, the best vein in the 

 Keewatin has been No. 26 on the Nipissing. 



ORES AND MINERALS. 



The more important ores in the veins under consider- 

 ation are native silver — associated with which is usually 

 some dyscrasite, argentite, pyrargyrite and other compounds 

 of the metal — smaltite, niccolite and related minerals. 

 Many of the minerals occur mixed in the ores, and for this 

 reason some of them have not been clearly identified. 

 Another character of the minerals, which renders their 

 identification difficult, is the fact that most of them occur 

 in the massive form. Crystals when present are small, 

 being frequently almost microscopic in size. The following 

 minerals have been identified and can be convenientlv 



classed under the headings : 



7—7 



