Plate VII. 



Microscopic characters of the four chief types. 



Fig. i represents the acid type or charnockite proper, which is composed of 

 colourless quartz and microcline with a small amount of hypersthene and opaque 

 black iron-ores. Specimen No. 9,658. 



Fig. 2 shows the common variety of "intermediate" composition from the 

 Shevaroy Hills. Hornblende and augite generally accompany the hypersthene. 



Fig. 3 represents the typical basic variety from near St. Thomas' Mount 

 (No. 9,657), which is composed of water-clear, basic plagioclase, hypersthene, 

 augite, opaque, black iron-ores and smaller quantities of hornblende and apatite. 



Fig. 4 shows a section of pyroxenite which is composed essentially of hyper- 

 sthene and augite, generally with hornblende, hercynite and, rarely, olivine (No. 

 9,672). 



All the sections have been drawn under low powers magnifying about 15—20 

 diameters. 



