REPORT OF THE DIRECTOR I9II 165 



the distribution of the deposits, which has previously been referred 

 to only incidentally. 



When the pyrite localities are indicated on a map it is at once 

 apparent that in a general way they conform to the prevailing 

 northeast and southwest trend of the Grenville belts of the region, 

 this trend corresponding approximately with the strike of the rocks. 

 It should not be inferred,- however, that the various mines occur 

 along a straight line, for such is not the case, although the first four 

 localities described do not vary widely from such an arrangement. 

 This distribution of the deposits is the result of what may be taken 

 as the second important feature to be mentioned, that is the constant 

 association of the pyrite with Grenville rocks, which occur as long, 

 narrow belts surrounded, and often broken across, by great areas 

 of granite gneiss. This association of the pyrite with metamor- 

 phosed sediments rather than with the more extensive areas of 

 igneous rocks, is a very striking feature of the deposits. Further- 

 more the association is not only with the Grenville but with a par- 

 ticular variety of the Grenville rocks, the so-called rusty gneisses, 

 rocks which appear to be the products of metamorphism of impure 

 sandstones and shales. 



As to the possibility of the pyrite occurring not only in a certain 

 kind of rock but in a certain definite horizon, a conclusion seems 

 justified despite the dangers attending the use of ordinary methods 

 of stratigraphy in dealing with the Grenville. 



The Styles and Farr mines show such similarity of rock succes- 

 sion as to suggest the possibility of identity of horizons. The 

 Hendricks pit, while showing limestone below the ore instead of 

 having it above also, as these do, has a heavy thickness of gneiss. At 

 the Cole mine scarcity of outcrops leaves relations uncertain, but 

 this very scarcity indicates the absence of the heavy gneiss which 

 overlies the ore at the Hendricks pit, though this latter locality is 

 nearer the Cole than the others. At Stella the section is totally dif- 

 ferent in its details from all the preceding localities ; the same is 

 true of Pyrites, although here of course the great intrusion of 

 gabbro would suffice to account for such dissimilarity. Combining 

 these data, it seems necessary to conclude that the pyrite, though 

 confined to a certain type of rock in the Grenville, is not limited to 

 any definite horizon. 



This occurrence of the pyrite in the one type of rock is another 

 important feature of the deposit which must be considered in any 

 hypothesis framed to account for its origin. In dealing with this 

 phase of the problem there is a serious practical difficulty. All 



