from red-brown to pale yellow-brown. Nearly as abim.hi-t 

 as the biotite is a purple titaniferous augite, generally in 

 roughly prismatic grains with a high extinction angle, 

 occasionally ophitic. It is often wrapped round by the 

 biotite, which in such instances is also partly ophitic. 

 Hornblende also occurs with strong pleochroism (brown to 

 red-brown) in almost idiomorphic crystals which may be 

 primary. Apatite is a very abundant accessory, occurring 

 in long prisms ; a few plates of ilmenite also are present. 

 Chlorite is a very abundant decomposition product, occur- 

 ring and replacing felspar, but also in large irregular 

 patches not definitely after any one mineral. It is yellow 

 green in colour, but where after biotite it is blue-green. 

 Very fine grained dust like carbonates are also present. 



The most common rock however is of a basaltic character, 

 even in band specimens it may be seen how very marked is 

 the flow structure of the felspars, and sections show the 

 rock to be hyalopilitic. (See Plate 3 /, fig. C.) The felspars 

 are in idiomorphic laths of labradorite, twinned on the 

 albite and carlsbad and occasionally on the pericline law, 

 which is less common for microlites, the mesostasis is of 

 grey-brown glass containing octahedra and small skeleton 

 crystals (plates) of magnetite, and green chlorite. This is 

 sometimes in idiomorphic areas probably pseudomorphous 

 after a pyroxene. Some carbonates are scattered about in 

 irregular grains or sharply defined rhombohedra. An 

 analysis of the rock gave the following figures (A) from 

 which the norm (B) and the systematic position was cal- 

 culated :— 



A B 



SiO, 48-30 Anorthite 31-14 



Al 2 O s 20-20 Albite 2830 



Fe 2 3 323 Orthoclase 1334 



FeO 5 82 Diopside 483 



