119 
TRANSITION-ROCK BETWEEN ARFVEDSONITE-GRANITE 
AND PULASKITE: THE QUARTZ-SYENITE. 
The arfvedsonite-granite of Ilimausak rests, as previously 
mentioned (see p. 79), on a relatively thin sheet of quartz- 
syenite and this in turn is underlain by the pulaskite. The 
thickness of the quartz-syenite-sheet varies from 0 to about 
20 meters. It is connected by gradual transitions both with the 
arfvedsonite-granite and with the pulaskite, and it may be re- 
garded, either as a lower border facies of the granite charac- 
terised by a relatively low content of quartz, or as an upper 
quartz-bearing border facies of the pulaskite. 
The quartz-syenite sheet reaches its maximum thickness in 
the mountain slopes above North Siorarsuit. It is here — to- 
gether with the lowermost part of the, granite and the upper- 
most part of the pulaskite — intensely red-coloured. The size 
of the grain is most frequently about the same as that of the 
granite but irregular bands:of a somewhat less coarse-grained 
structure are also found. 
The felspar or the quartz-syenite is a perthitic microcline- 
albite closely agreeing with that of the arfvedsonite-granite of 
Ilimausak. It shows a very slight tendency to idiomorphism 
against the quartz. This latter mineral occurs rather abundantly 
in the uppermost portion of the sheet but downwards the 
amount gradually decreases. In the middle part of the sheet 
only very little quartz is visible to the naked eye. Under the 
microscope a somewhat larger number of quartz-grains are 
detected; as a rule they are much smaller than the felspar- 
grains and are often associated in groups of four, five, or more 
grains. In the lowermost portion of the sheet quartz is only 
present in a very small amount. 
The original dark minerals of this rock have been entirely 
converted into fine-grained aggregates of iron oxides and hydrous 
iron oxides intermingled with abundant fluorite and a little 
