153 
The sequence of crystallization when oniy the main consti- 
tuents are considered is as follows: 
I. Sodalite 
II. Nepheline and eudialyte 
ИГ. Felspar 
IV. Ægirine, and finally arfvedsonite. 
This applies to the time of crystallization of the bulk of each 
constituent. But it will be evident from what has been said 
above that the periods of growth of the different minerals 
largely overlap one another. ,, Thus, the main portion of the 
sodalite which is rich in inclusions is no doubt older than the 
nepheline, but the crystallization of sodalite has slowly con- 
tinued contemporaneously with that of nepheline and far beyond 
the time when felspar began to crystallize. On the other hand 
there are no indications whatever that sodalite or nepheline 
crystallized later than felspar, and this is a very noticeable 
difference from the sodalite-foyaite where felspar is the most 
idiomorphic mineral. As to the ægirine and the arfvedsonite 
their behaviour is the same as in sodalite-foyaite (see p. 137). 
Chemical composition. — Owing to the extremely large 
size of grains of the naujaite great care was needed in the 
selection of specimens for the purpose of chemical examination. 
Two analyses have been made with the results shown in the 
table on the next page. The first analysis (No. 6) was made on 
specimens collected as typical representatives of the naujaite as 
it appears at Kangerdluarsuk. For the second analysis (No. 7) 
typical specimens were taken at Nunasarnak, on the northern 
side of Tunugdliarfik. 
From the chemical analyses the mineral composition is 
approximately found to be the following!: — 
1 With regard to the chemical composition of the minerals the same as- 
sumption have been made here as in the calculation of the sodalite- 
foyaite (p. 142). 
