708 STEINAR FOSLIE , 
17 per cent ferrous silicate, the monoclinic pyroxene is a diallage. 
The plagioclase is always bytownite, about Ab.,Ang,, nearly with- 
out zones, and occurring interstitially between the other minerals. 
In the normal norite the minerals are: Hypersthene with abous 
25 per cent ferrous silicate, poikilitic diallage in big individualt 
with hypersthene inclusions, labradorite-bytownite, often with 
zonal structure and varying composition, from 50 to 80 per cent 
An, and some primary biotite. Uralitization occurs in many parts 
of the field, but has no interest in this connection. The consid- 
erable variations in this rock seem exclusively to be due to quan- 
titative variations in the relative proportion of pyroxene and 
plagioclase. ‘The monomineralic rocks, anorthosite or pyroxenite, 
are however, never developed. 
The quartz-norite contains iron-rich hypersthene with 40-45 per 
cent ferrous silicate, much diallage, which is here not poikilitic, 
but crystallized at the same time as the hypersthene, and further 
generally plenty of biotite. The plagioclase is labradorite with 
marked zonal structure, from 40 to 55 per cent An. Besides, this 
rock always contains small amounts of microcryptoperthitic ortho- 
clase, rich in natron, and of free quartz. 
The aplitic granite dikes contain quartz, oligoclase with 26 
per cent An, non-perthitic microcline, and a little muscovite and 
biotite. 
The pegmatitic granite dikes contain cntarens perthitic microcline 
with a faint green color, and black tourmaline. The perthite 
consists of 87 per cent microcline and 13 per cent albite-oligoclase 
with the composition Abs,An,,. 
The chemical composition of the differentiation products is seen 
from the analyses in the following table, where the calculated norm 
is also given. 
The mode of these rocks naturally differs somewhat from the 
norm, even apart from secondary processes. So the potash, 
instead of forming orthoclase, partly enters into plagioclase and 
biotite, while part of the lime together with aluminia enters pyrox- 
enes instead of plagioclase. 
After an exact microscopic measurement, I give the mineral 
composition actually found in the normal norite and the quartz- 
norite, corresponding to the analyses No. 3 and No. 6 respectively. 
