I $2 HOLLAND: CHARNOCKITE SERIES. 



the quartz presents a pseudo-dendritic arrangement with the felspar ; 

 but isolated spindle-shaped blebs also occur in the plagioclase 

 and from their refractive index and double refraction appear to be 

 quartz. These small blebs are in crystallographic continuity with 

 one another over large areas. The fusiform inclusions which give 

 the microperthitic structure to some of the non-striated felspars are 

 generally crossed by cleavage cracks, by which means they are 

 readily distinguished from the small blebs referred to above as 

 doubtfully composed of quartz. 



The irregular distribution of the ferro-magnesian silicates 

 amongst the other constituents has already been referred to as a 

 noticeable characteristic of the intermediate group (Nos. 9779 

 and 9*787). Sometimes only hypersthene is present, in which case this 

 irregularity of distribution is not so marked ; but generally both 

 augite and hornblende accompany the hypersthene, whilst biotite, in 

 most cases probably of secondary origin, occurs in nearly all varie- 

 ties of this group. This tendency of the ferromagnesian silicates to 

 congregate in groups — microscopic patches — was noticed by Hatch 

 in the case of very similar pyroxene granulites from Madagascar 

 {Quart. Journ. Geol. Soc, Vol. XLV (1889), p. 344). 



One of the specimens of this group is interesting on account 

 of the large quantities of graphite it contains (No. 10*670). Besides 

 graphite, the rock is composed of hypersthene, quartz, an unstriped 

 felspar with microperthitic inclusions, oligoclase. pyrite, titaniferous 

 iron-ore, and a small quantity of garnet. 



The large crystals of hypersthene in this rock are extremely well 

 schillerized and the quartz contains the hair-like inclusions noticed 

 before (p. 138). The graphite is scattered in small flakes through the 

 rock and is regularly distributed like a normal constituent. A con- 

 siderable quantity was easily isolated by means of a heavy liquid 

 from the other constituents of the crushed rock. It floated in the 

 liquid after the precipitation of all the other minerals, and began to 

 sink itself on reducing the specific gravity of the liquid to 2*1. 

 Graphite has recently been found as minute scales scattered 



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