PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 925 



Quartzyte. Pyroxenyte.] 



of orthorhombic pyroxene showing the twinning of 104. It is here plain that 

 the orthorhombic pyroxene was of later origin than the monoclinic. One section. 

 Age. Keewatin (condition of the jaspilyte). N. H. w. 



No. 399H. QUARTZYTE (vntli magnetite, hypersthene, etc.) 



E. y z N. E. y sec. 35, T. 61-12, near Birch lake. 

 Ref. Annual Report, xvii, pages 95, 138. 



Meg. Nearly all quartz, but with varying amounts of magnetite and hyper- 

 sthene. 



Mic. Quartz, "magnetite, hypersthene, cummingtonite, diallage( ? ) constitute this 

 rock about in the order named. It is a phase of the ferriferous beds which are com- 

 mon near the gabbro, and as a rock is difficult to name. It is always accompanied 

 by some form of the well-known muscovadyte. 



Age. Pewabic quartzyte, a phase of the jaspilyte of the Keewatin, under the 

 action of the gabbro revolution. N. H. w. 



No. 402H. PYROXENYTE. 



N. E. M S. W. M sec. 35, T. 61-12, near Birch lake. 

 Ref. Annual Report, xvii, pages 95, 138. 



Meg. Hornblendic and magnetitic. 



Mic. Hypersthene and augite are closely associated in the composition of this 

 rock, the former being the later to be formed. With these, especially in the hyper- 

 sthene, are also a little quartz and magnetite. One section. 



Age. Same age and genesis as No. 399H. N. H. w. 







No. 405H. PYROXENYTE. ( Ferriferous. ) 



N. % S. E. J4 sec. 24, T. 61-12, near Birch lake. 

 Ref. Annual Report, xvii, pages 95, 138. 



Meg. Quartz and iron ore in bands, alternating with bands of pyroxene. 

 Mic. Magnetite, augite and a little quartz. This is so heavily magnetited that 

 it might be taken for a lean iron ore. One section. 



Age. Pewabic quartzyte, same as No. 399H. N. H. w. 



No. 406H. PYROXENYTE. ( Ferriferous. ) 



S. E. % N. E. % sec. 35, T. 61-12, near Birch lake. 

 Ref. Annual Report, xvii, pages 94, 138. 



Hornblendic. 



Mic. Augite, hornblende, biotite, magnetite, apatite, quartz. The apatite is some- 

 times within magnetite and sometimes within feldspars, of which a few are seen in 

 the slide, though they are considerably altered. Two sections. 



Aye. Same age and genesis as 399H, but more allied to muscovadyte. 



