1922] Whitman: Genesis of the Ores of the Cobalt District 271 



calcite is more generally the filling of barren veins ; but to this rule 

 there are many and. notable exceptions. 



Native bismuth, dyscrasite, native silver, argentite, and proustite 

 frequently occur in fractures in the ore bodies or in fractures in their 

 walls, commonly penetrating the walls in this manner for distances 

 up to 20 feet. This apparently secpiential relation to the vein matter 

 will be explained on a different basis in a later section. 



THE GENESIS OF THE ORES ■ 



Believing it to be a more scientific method of treatment, I have 

 endeavored to separate, as well as possible, description and inference. 

 Inference necessarily enters into description in the guise of interpre- 

 tation, and description to some extent must accompany inference in 

 cases where its value and bearing would not otherwise be fully appre- 

 ciated. However, it is the purpose of this section of the paper to 

 present as exclusively as possible the results of research without which 

 the statistics would be valueless ; for no one can be in such a good 

 position to correlate the facts of the case and indicate their significance 

 as the one who gathered them ; although he may not be able to present 

 them in their entirety. 



Diastrophism 



Major structural axes. — A quotation in a previous paragraph 

 shows that Miller suspected a genetic relationship between the cobalt- 

 silver veins and certain major structures which are dominant through- 

 out the mineral-bearing region, and which are indicated on the maps 

 by long NE-SW and NW-SE chains of depressions, occupied for the 

 most part by rivers and lakes. My observations have seemed to con- 

 firm those suspicions in the sense that these lines appear to be expres- 

 sions of the general determining structural factor connected with the 

 genesis of the vein fissures. 



These and similar physiographic axes extend over a good portion 

 of the pre-Cambrian area in Canada, but seem to be particularly pro- 

 nounced on the map in the provinces of Ontario and Quebec. Their 

 rule of arrangement apparently is that in any given area where system 

 is observable, not more than two systems dominate, one being the com- 

 plement of the other, save where one system represents the resultant 

 between the other and its complement. In many localities described 

 in the geological literature of Canada, these lines are known to be, or 



