60 Rocks of Noyang. 



This calculation shows a probability that the remainder, 

 after providing for the rnuscovite-niica on the basis of '52 

 Mol. of K o 0, gives a chloritic mineral of the constitution 

 3 Si0 2 , 3~R 2 33 3 RO, 3 R 2 0, with a surplus of 1594 

 Mol. of SiOo for the quartz. This rock, therefore, has the 

 following percentage composition, disregarding the apatite 

 and the limonite : — 



Chloritoid 85/29 



Muscovite ... ... ... ... 15-05 



Quartz 49-66 



100-00 

 And the micaceous minerals are, to quartz, very nearly in 

 the molecular proportion of 1" to 1* 



Near the contact of the quartz-mica-porphyrites and the 

 sediments at the Haunted Stream, about two miles from the 

 Tambo River, I found fine-grained beds resembling those 

 just described, and, as in the other case, alternating with 

 sandstones. The dip was here N 10° W at 80°. I found 

 this rock to be made up in great measure of the uniaxial 

 chloritic mineral which I had before observed in the Shady 

 Creek rocks, together with muscovite, which here again was 

 disposed in two directions, producing a net-like appearance. 

 Together with these were some quartz grains and ores of 

 iron, magnetite, and brown iron ore. 



In the same neighbourhood, but somewhat nearer to the 

 Tambo River, I found the sediments more metamorphosed. 

 One which I examined I found to be of the following com- 

 position : — (1) Angular grains of quartz, with a few minute 

 fluid cavities ; (2) brown mica in small flakes ; (3) a little 

 colourless mica, perhaps muscovite. 



At the junction of the Haunted Stream with the Tambo 

 River, I found the contact schists well developed. For some 

 half mile up the river the schists are traversed by joints 

 dipping east at about 25°. At the contact itself the bedding 

 planes of the sedimentary rocks are almost obliterated, but 

 where I could make it out I found the bedding to be at high 

 angles on a strike east and west. The schists are traversed 

 by a number of strong porphyritic dykes. I observed inclu- 

 sions in the quartz-mica-diorites at the immediate con- 

 tact, which somewhat resembled the dark-coloured patches 

 which are so common in these rocks. These, however, were 

 true inclusions of foreign rocks, and not merely aggre- 

 gations of the more basic elements of the diorites. I exa- 



