126 
sodalite. The name which was given during the field work has 
been retained in this report for practical reasons. It should, 
however, only be regarded as a provisional name, for the rock, 
upon closer examination, has proved to belong to the melano- 
cratic division of the nepheline-syenites. 
The naujaite is still more coarse-grained. It is charac- 
terised by a very high amount of sodalite and a peculiar poi- 
kilitic structure. Since it differs considerably from any other 
known rock and since it is of wide distribution within the Ш- 
mausak region it may be regarded as the most characteristic 
rock of this complex. 
The lujavrites of Iimausak are more or less fine-grained, 
melanocratic rocks rich in needle-shaped egirine or arfvedsonite. 
Some varieties of the egirine-lujavrite of this locality are much 
like the original lujavrite from Kola as described by W. Ramsay. 
The extension of the lujavrite-group to comprise all the varieties 
which are described as lujavrites in this report is in accordance 
with the remarks of Ramsay as to the use of this term which 
was originally introduced by Brôccer!. 
The kakortokite is structurally related to the foyaites, che- 
mically to the lujavrites. The main body of this rock is more- 
over characterised by a most extraordinary banded structure. 
FOYAITE. 
The pulaskite-sheet of the Ilimausak batholite passes down- 
wards into the coarse-grained foyaite which constitutes the 
uppermost sheet of the nepheline-syenitic complex. The foyaite 
in turn is connected by insensible gradations with the under- 
lying sodalite-foyaite. For this reason it is impossible to indicate 
the accurate thickness of the foyaite-sheet. As far as observa- 
tions go the approximate thickness varies between 0 and 10 meters, 
1 W. Ramsay, Das Nephelinsyenitgebiet auf der Halbinsel Kola II. Fennia 
ХУ т: 2, 1898. DEA 
