734 
Geology. — “On the formation of primary parallel-structure in 
lujaurites.” By Dr. H. A. Brouwer. (Communicated by Prof. 
G. A. F. MOLENGRAAFF). 
(Communicated in the meeting of October 26, 1912). 
In an important memoir of the late Professor N. V. Ussine ') 
we find a detailed discussion on the question of the origin of schis- 
tose structure in Injaurites. It is explained as a consequence of 
fluctuation, in contradiction to Ramsay’s?) view, who admits a slow 
cooling and undisturbed crystallization of the magma for the rocks 
of the peninsula of Kola. 
In my description of the Transvaal nepheline-syenites*) the name 
lujaurite was extended to rocks without parallel-structure, charac- 
terized by the oceurrence of fine-needle-shaped crystals of aegirine 
in abundance. The parallel-structure where it occurs was explained 
as aconsequence of a crystallization influenced by one-sided pressure, 
which view will be now more explicitly explained. 
Geological connection with accompanying rocks. 
In the peninsula of Kola no remains of the roof of the intruded 
batholite have been preserved and thus it is not certain whether 
the lujaurites are the first products of consolidation in the marginal 
zone of the igneous mass. In the Pilandsbergen (Transvaal) the 
schistose varieties are often still surrounded by a border of nephe- 
line-syenitie or syenitie rocks, whilst in the Greenland intrusions 
which have been very carefully examined, the lujaurites form the 
lowermost rocks of a stratified batholite which has been denuded. 
The last mentioned rocks are covered by a very coarse-grained 
foyaitie rock (naujaite) the erystals of which are sometimes a few 
decimeters large; it is characterized by sodalite poikilitically surround- 
ed by all other minerals. Pegmatitie segregations are found chiefly in 
a horizontal position, whilst in the rock itself a more or less hori- 
zontal stratification in thick layers is indicated. Towards the upper 
portion the naujaite gradually passes into a sodalite-foyaite, whilst 
downwards it is connected with the underlying lujaurites by a breccia- 
ted zone of transition. This breccia-zone is formed by strata of lujau- 
1) N. V. Ussine, Geology of the country around Julianehaab, Greenland. Med- 
delelser om Gronland, vol. XX XVIII, and Muséum de Min. et de Géol. de |’Univer- 
sité de Copenhague, Communications Géologiques NO. 2, 1911. 
2) W. Ramsay, Das Nephelinsyenitgebiet auf der Halbinsel Kola, I and IL Fennia 
11 and 15, N°.2. Helsiegfors 1894 and 1899. 
3) H. A. Brouwer, Oorsprong en samenstelling der Transvaalsche nephelien- 
syenieten. ’s Gravenhage, Mouton & Co, 1910. 
