WHITE : OATIiAND COMPLEX OF IGNEOUS ROCKS. 
125. 
Smaller grains are enclosed poecilitically in the hornblende. 
Twinning is fairly common, but there are very few traces of 
cleavage left. The mineral is mostly uralitic, and often now 
chloritic, but frequently it appears as colourless malacoHte, witk 
refractive index greater than hornblende, extinction angles of 
about 44 degrees, and strong birefringence. In one section 
there is an approach to the diabase type with a few crystals of 
felspar in a granular state, but with fair outlines enclosed in the 
marginal zones around the augite. These enclosures range from 
.1 mm. by .1 mm. to .56 mm. by .26 mm. in section. The augite^ 
has therefore continued to grow after the now oxidised biotite 
and the plagioclase have commenced to form. Magnetite dust 
is also present in a zonary arrangement near the margins. 
The proportion of augite present in this type gradually 
iQcreases from 38.3 per cent, to 66.8 per cent, of the total content. 
In the section showing the intruded thread of quartz, augite 
is associated with the clear plagioclase crystals. It is here- 
perfectly clear malacolite with high refraction and birefringence. 
One crystal extinguishes at 47 degrees, and in another the cleavage 
lines make an angle of 85 degrees. 
Iron Ores are present in variable quantity, specially associated 
with the hornblende and augite. In the former the larger 
idiomorphic crystals appear to be magnetite and the smaller 
crystals in the augite are ilmenite now changing to leucoxene. 
ORDER OF CRYSTALLISATION IN THE BASIC TYPE. 
The allotriomorphic character of so many of the minerals 
indicates that several of them probably ceased to crystallise 
almost simultaneously but by a comparison of the sections the 
following is held to be the approximately correct order in which 
they commenced to form. 
1. Ilmenite, magnetite and apatite. 
2. Augite and some brown hornblende. 
{Felspar. 
Biotite. 
Brown and greenish hornblende. 
