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or less homogeneous main portion are included numerous areas 
of oligoclase showing an extinction angle of about + 4°. These 
areas have the form of an irregular oval and are elongated par- 
allel to the direction of the cryptoperthitic lamellation. In 
sections perpendicular to (O10) the oligoclase areas show an 
imperfect rectangular form and are slightly elongated parallel 
to the trace of (010); the twin lamellation is not easily per- 
ceptible. The cryptoperthitic lamellation is also observed in 
these sections and its direction is perpendicular to (O10). 
In other varieties of the rock, containing more quartz, 
the felspars consist of orthoclase and albite in very irregular 
spotty and dotted microperthitic intergrowth. Sometimes the 
boundary of the crystals consists of pure albite and sometimes 
pure albite is observed in separate crystals. In a specimen of 
nordmarkite from Nungmiut, north-west of Narsak, the felspar 
is rather peculiar. In this specimen larger, scattered crystals 
of oligoclase are found, while most of the felspars consist of 
microperthitic microcline-albite and this microcline shows a 
very marked cross-hatching. It is otherwise extremely rare to 
find cross-hatched microcline in the post-Devonian igneous rocks 
from this area. 
The felspar is generally a little weathered and under the 
microscope proves more or less turbid. In the perthitic cry- 
stals the orthoclase is always more weathered than the pla- 
gioclase. 
Quartz commonly occurs as a subordinate component, 
sometimes, however, it is almost entirely wanting. It fills 
angular interspaces between the felspars and the other mi- 
nerals. 
The structure is a typical hypidiomorphic-granular one 
without any tendency to a parallel arrangement of the consti- 
tuents. Apatite and after that iron-ore and augite are the most 
idiomorphic components, next comes felspar. The other dark- 
coloured minerals are as a rule less idiomorphic than the 
