18 
Transactions of the Boyal Society of South Africa. 
right angles for a short distance. They rarely ramify. Wherever it is 
possible to estimate they are vertical, and weather out as vertical wall-like 
bodies which are very much rectangularly jointed. The lenticular-shaped 
bodies are fairly numerous, but fewer than the veins. They are up to 
several hundred feet in greatest length, their greatest width commonly 
being half their length. They narrow out at their extremities to a few 
feet. They often possess a horizontal bedded structure, probably due to 
jointing. 
The whole of most bodies and the central parts of nearly every one are 
composed of a uniformly fine-textured holocrystalline granite, which has a 
characteristically granular structure. This rock is composed essentially 
of felspar, quartz, and biotite. Accessory sphene is present in some ; and 
chlorite, zoisite, kaolin, and sericite are alteration products. Quartz is 
generally subordinate to felspar. Biotite is commonly abundant, but in 
some rocks is absent. The felspars tend to be idiomorphic, and in some 
rocks are porphyritic ; they are chiefly acid plagioclases, but lime-free 
felspar is probably common, whilst basic andesine to labradorite is present 
to a small extent. 
The mica is strongly pleochroic — deep foxy brown to golden-yellow. 
It is poorly crystallized and forms irregular ragged crystals and aggregates 
intergrown w^ith both felspar and quartz. It is altering to chlorite. 
The aplite veins resemble the granite, but many have knots of quartz, 
and some, patches of felspar and quartz graphically intergrown. 
The quartz veins are only a few inches wide, and are composed of 
nearly black quartz with a curious platy structure. Felspar is present in 
some, when the vein becomes a pegmatite, but is completely absent in 
others. In some instances quartz occupies the sides of a small 6-inch 
granite vein, and in places may occupy nearly the complete width of the 
vein. 
The norite pegmatite occurs typically as a marginal facies of the 
granite veins. The rock is coarse-grained, in places very coarse. The 
structures presented are diverse and change rapidly. Coarse granular, 
coarse pegmatitic, fine pegmatitic, and even graphic structures obtain. 
The rock is composed essentially of white felspar and a pistachio-green 
laminated scaly bastite pseudomorphous after rhombic pyroxene ; milky 
quartz is an important constituent in some parts, but is generally absent, 
chloritized biotite is also present in some specimens. The bastite pseudo- 
m^orphs are more or less idiomorphic towards the felspar, in places 
forming crystals 8-10 centimetres long by 2-3 centimetres across ; many 
of these crystals are skeletal and remarkably intergrown in a graphic 
manner with quartz and felspar. The bastite pseudomorphs further 
present a remarkable character in being partially composed of dark green 
fibrous strongly pleochroic amphibole. The amphibole forms a minutely 
