PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 651 



Greenstone. Marble. Conglomerate.] 



which, owing to the extreme fineness of the rock and the thickness of the section, 

 cannot be determined, but which appears to be calcite, or muscovite. There are 

 numerous feldspar fragments in the coarser bands, and one nearly entire crystal 

 lying with its greatest dimension parallel with the banding. One section. 



Aye. Archean (Upper Keewatin). N. H. w. 



No. 1068. GREENSTONE. 



From the hill a little north of the second narrows of Ogishke Muncie lake, east side of sec. '24, T. (i.j li. 

 Rcf. Annual Report, xv, pages 371, 372, 396; Annual Report, xvi, page 90; Annual Report, xvii, pages 

 19G, 205. 



Meg. Collected under the name doleryte. 



Mic. The whole slide is composed of a very fine, green element, like some species 

 of chlorite, with scattering remnants of feldspar (and secondary feldspar) and calcite. 

 There were sundry small geodic cavities which have become filled with the same 

 chloritic substance. Separating this chlorite from the walls of the original cavity is 

 a coating of a transparent mineral of very low double refraction, uniaxial and prob- 

 ably quartz. One section. 



Age. Archean (Keewatin). 



Bemark. In this rock there is no trace of ophitic structure. Calcite constitutes 

 nearly one-half. There are a few magnetite grains, with accompanying leucoxene. 



N. H. w. 

 No. 1069. MARBLE (with greenstone i-nclmwns). 



Hill just northwest of the last; sec. 24, T. 65-6. 



Ref. Annual Report, xv, pages 371, 396 ; Annual Report, xvi, page 95 ; Annual Report, xvii, page 199. 



M.c(j. Rusty, calcareous, fine grained. (Compare No. 746.) Rises about ten 

 feet. 



Mir. What remains of the slide, which is accidentally much wasted in the 

 preparation, shows a rock like the last, but containing more calcite. One section. 



Aye. Archean (Keewatin). 



Remark. As this rock was collected under the same " irony conglomerate," it 

 is probable that the slide does not fairly represent it. N. H. w. 



No. 1070. CONGLOMERATE. (Runty. ) 



Rapids of the stream connecting Ogishke Muncie and Town Line lakes; sec. 13, T. 65-4. 

 Rcf. Annual Report, xv, pages 372, 396. 



Meg. Pebbly, schistose conglomerate. 



Mi<: There is a little quartz amongst the pebbles of this conglomerate, but 

 generally the pebbles are of some greenstone, either very fine grained and with much 

 calcite or thickly porphyritic with microlitic feldspars, in both cases so altered that 

 the hornbleudic ingredient is chloritized. In the finer matrix embracing these is 



