REPORT OF THE DIRECTOR IQII I 53 



While in all these cases the pyrite is manifestly introduced into 

 its present position very late in the history of the rock, the question 

 arises : Has it been brought into the rocks from an outside source 

 subsequently to their formation or is it an original constituent 

 which has merely undergone secondary migration and recrystalliza- 

 tion? The answer to this question may be different for the. pyrite in 

 gneisses, on the one hand, and for that in pegmatites, on the other, 

 but as in either case the whole problem of the origin of the ore 

 bodies is involved, the consideration of the matter is deferred for the 

 present. 



THE STELLA MIXES 



About five miles northeast of the Farr mine are located the Stella 

 mines, much the most extensive workings of the pyrite region. In 

 many respects the geology is similar to that of the localities 

 already mentioned, but at the same time there are some striking 

 differences. The mines lie in a Grenville belt, with extensive 

 development of rusty gneisses southward and heavy limestone on the 

 north. At the mines the exposed section begins on the south with a 

 coarse, rather massive, very dark hornblende gneiss, quite unlike 

 any rock shown at the other localities. This rock forms a ridge 

 south of the new Anna shaft, on the lower ore body, which is the 

 next member of the series and which in its natural exposures is a 

 typical rusty gneiss. Above this comes another gneiss forming a 

 high ridge between the two ore bodies. At the bottom, this rock is 

 light gray and appears fairly acid, but higher up it becomes dark 

 and hornblendic, resembling closely the lower hornblende gneiss, and 

 then finally becomes acid again toward the top. Next comes the 

 rusty gneiss of the upper ore body, and this is followed in turn by a 

 light gray mica gneiss, making up a considerable ridge, with lime- 

 stone to the north. This generalized section is represented in 

 figure i6. 





Fig. i6 Hornblende gneiss shown by crossed hachures 



As compared with sections at the other localities, the entire 

 absence of limestones is perhaps the most striking feature. The two 

 distinct main ore horizons are also worthy of note, while perhaps 

 more important is the great development of gneiss. The high ridge 

 of gneiss above the ore at the Hendricks mine is in some ways 



