68 



The Sedimentary, Metamorphic, 



but I did not find them so pleochroic as I should have 

 expected them to be. 



I made a quantitative analysis of this sample, which I 

 subjoin : — 



No. 



1.- 



— Phyllite. 





P 2 5 ... 







•13 



Si.0 2 





. . . 



56-33 



Al.,0, ... 







22-94 



Fe. o 3 ... 







219 



Fe.O 







4*54 



Mn.O 





. . c 



•tr. 



Ca.0 







•25 



Mg.O 





. . . 



3-27 



K.O 





. . • 



610 



Na. 2 .,; 







•88 



H 2 ... 



moisture 



3-87 





100-50 



Hygroscopic 



•80 



Sp. grav. 



.. 





.. 2-75 



Allowing for the P 2 5 and a corresponding amount of 

 Ca.0 as apatite, and for Fe 2 3 and H 2 as hydrated iron 

 ore, which in parts forms thin coatings in the rock, there 

 remain the proportions of 1*877 Mol. Si.0 2 , '445 Mol. R 2 3 , 

 •293 Mol. R.O., and '547 Mol. R 2 0, which very nearly close 

 when calculated as alkali- mica, magnesia-mica, and quartz, 

 giving a proportion of 1*5 : 1*5 : 1, respectively ; or of mica 

 to quartz as 3 to 1. 



The second sample which I selected for examination and 

 analysis represents the sandstones. As seen in thin slices 

 this rock has an approach to foliation ; but this foliation also 

 coincides with the planes of deposit. It is made up of a 

 large number of angular grains of quartz, set in a ground- 

 mass of smaller quartz granules, together with a few grains 

 of triclinic felspar, and, relatively, a considerable amount of 

 micaceous material. In this rock the quartz grains have a 

 tendency to lie with their longer diameters parallel to the 

 obscure foliation of the rock. 



The felspar fragments are of two kinds. One is compara- 

 tively fresh in appearance, and it is compound in structure, 

 and with low obscuration angles. The other is dull looking, 



