PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 921 



Conglomerate. Mica schist.] 



the feldspars and quartzes to come exactly into contact. In that case these minerals 

 also appear to be interlocked as if they had been connected originally in a common 

 foreign source. In short, the fine green debris seems to embrace a quartzose coarser 

 debris derived from granite. 3. With a few large grains of quartz and of a micro- 

 perthited feldspar (orthodase ?) is much of the same green fine substance, which 

 shows not only hornblende in its composition, but also much of an amorphous green 

 chlorite. In this green hornblendic mass are also included as foreign grains a few 

 crystals of apatite, one of which is abnormally slightly biaxial. 4. Same as No. 3, 

 even to the occurrence of apatites in the green matrix. 5. With a diminution of 

 detrital quartz and feldspar there is an appearance of granulitic and micro-granulitic 

 quartz, which is distinctly separable from the detrital quartz, both in its boundaries 

 and in its microscopic aspect. The detrital quartz extinguishes in a shadowy manner, 

 and is in large grains, but the granulitic quartz is fresh and fine, and each grain is 

 throughout simultaneous in its extinction, while sometimes the hornblendic fibrous 

 development encroaches on it, sending sharp needles into it, yet there are pebbles 

 of granulitic quartz, as of the shadowy quartz, some of them being much coarser and 

 some much finer than the general matrix of granulitic quartz. One large round 

 pebble of granulitic quartz is coarse, and lies in a matrix of very fine granulitic 

 quartz, the separating boundary of the pebble being distinct through its whole 

 circumference. Other similar pebbles are much finer than the granulitic quartz matrix 

 in which they lie. Other pebbles are partly of granulitic quartz and partly of the 

 green matrix, while in still other places the green matrix itself is gathered in spots 

 resembling pebbles. The green substance is almost entirely of hornblende. 6. In the 

 midst of a general groundmass of micro-granulitic quartz, varying in fineness, are 

 roundish spots or pebbles of the green hornblendic "matrix," but here the horn blende 

 is so stained by iron oxide that it appears red, and instead of acting as matrix, it is 

 surrounded by the granulitic quartz in the manner of a matrix. Six sections. 



Age. Animikie(?) 



Remark. When collected, this conglomerate was supposed to be a part of the 

 Animikie, but both the field and microscopic characters indicate that some parts are 

 in the Keewatin. The entire series of interesting facts can apparently only be 

 explained by supposing that here the Pokegama conglomerate, the base of the 

 Animikie, lies non-conformably on the conglomeratic base of the Upper Keewatin, 

 and that the latter exhibits, as it does at Saganaga lake, a gradual and almost imper- 

 ceptible transition to the underlying Archean, the difference of dip of the two form- 

 ations not being evident. N. H. w. 



No. 370H. MICA SCHIST (with cordierite). 

 Ref. Annual Report, xvii, pages 85, 136. 



Meg. Tough, black, heavy, but not magnetic. 



