165 
Analysis of pseudo-leucite(?) of ægirine-lujavrite. 
Per cent. 
SU) aude ire >14 
AL Olen 25.1 
NAS О 14.3 
KOR seth = tr 
H,O 87 
995 
The composition is that of an ordinary, slightly altered 
analcime. Between crossed nicols this analcime shows the usual 
‘eudnophitic’ birefringence. It contains numerous minute needles 
of egirine and arfvedsonite crowded in the central part of the 
crystals. Dr. Sreexsrrup who, in 1888, observed the icositetra- 
hedra in the lujavrite in several places both on the northern 
and on the southern side of Tunugdliarfik held them to be 
leucite or altered leucite. Indeed, as they behave like pheno- 
crysts it seems very unlikely that they are primary analcime- 
crystals, though the crystallographic orientation as indicated by 
the cleavage corresponds with the icositetrahedral form. И is 
probable, therefore, that they are pseudomorphs replacing original 
phenocrysts of leucite or some unknown mineral. 
Structure. — Although the egirine-lujavrite as shown by 
the mode of occurrence has crystallized under abyssal condi- 
tions its structure is very different from that of ordinary abys- 
sal rocks. The accompanying microdrawing (Fig. 17) will give a 
general idea of the principal features. In the first place it is 
to be noticed that the minerals of this rock do not show the 
pronounced sequence of crystallization characterizing the typical 
abyssal rocks: with the exception of the large poikilitic pseudo- 
phenocrysts of arfvedsonite, which have evidently been the last 
to crystallize, all the other minerals exhibit a marked tendency 
towards idiomorphic development. The most peculiar structural 
features, however, are the schistosity of the rock and the rela- 
tively small size of grain. It is true that varieties are also found 
which are almost devoid of schistosity; in such cases the size 
