143 
of ainigmatite by Forspere have been used. But as the actual 
composition of all these minerals in the rock may be more or 
less different from that given in these analyses the above cal- 
culation is only likely to give a very approximate idea of the 
relative amounts of the mineral components. 
NAUJAITE. 
The naujaite may be regarded as the most charateristic 
rock of the Ilimausak region. It covers a larger area than any 
other nepheline-syenite of this complex, and it is exceptional 
as to mineral composition and structure. It appears in the 
coast cliffs at most of the landing-places used by travellers 
going in search of rare minerals, and it has therefore long 
ago attracted attention. As a separate rock-type it was first 
described by Dr. Sreeysrrup who termed it ‘sodalite-syenite’ 1. 
The naujaite may be defined as an extremely coarse-grained 
nepheline-syenite, characterized by a very high content of so- 
dalite and by a peculiar poikilitic structure. 
Occurrence. — The naujaite reaches its maximum thick- 
ness, about 600 meters, at the inner end of Kangerdluarsuk. 
From this place it extends northward and northeastward all the 
way to Tunugdliarfik; north of this fjord it reappears and 
covers a considerable area around and below the arfvedsonite- 
granite. The total area where the naujaite is exposed to view 
may be estimated at about 24 km?. To this may be added the 
areas where it is covered by the other rocks or by the sea, as 
well as those from which it has been removed by erosion. In 
this way it is found that the original extension amounts to 
about 60 km?. As the mean thickness is estimated at 300 meters 
the total volume of this rock originally present within the 
1 Meddelelser om Grenland II, 1881, p. 35. — The term ‘sodalite-syenite’ 
is also used in later publications by STEENSTRUP, LORENTZEN, BOGGILD, 
UssixG and others. The reasons for the introduction of a new name have 
been given in the preceding chapter (p. 32). 
