167 
Chemical composition. — Three varieties of the ægirine- 
lujavrite have been selected for examination. The results are 
given in the table on the following page. The first analysis 
(No. 8) refers to a specimen of which the only felspathic con- 
stituent is microcline (as far as observed in the slices); it is 
possible, however, that the rock may locally contain albite and 
that the absence of this mineral in the slices may be casual or 
due to its conversion into analeime. The total amount of anal- 
cime in this rock is small and the relatively high content of 
water is mainly due to the fact that hydronephelite largely re- 
places the nepheline. 
The specimen of which an analysis is given in No. 9 dif- 
fers from the preceding in the proportion of felspars, albite 
being the dominant felspar while microcline occurs subordi- 
nately. Arfvedsonite is rather scarce and has partly been con- 
verted into acmite. Analcime is almost absent, but the outer 
zone of the nepheline-crystals has been transformed into 
sodalite, and the interior has partly changed into hydrone- 
phelite. 
The analysis No. 10 shows the composition of an ægirine- 
lujavrite in an advanced state of zeolitization. The egirine is 
intact but the great majority of the light-coloured minerals has 
been replaced by analcime. In each slice there may be found 
areas where only egirine and analcime are seen within the field 
of the microscope. Such areas at first sight give the impres- 
sion that the ægirine-needles are imbedded in a colourless 
base. Upon closer inspection, however, the contours of the 
original crystals of felspar, nepheline, and eudialyte are seen to 
be indicated by the arrangement of the ægirine-needles, and in 
other parts of the same slices remnants of these minerals may 
be found. 
A comparison of the figures given in the table will show 
that the analyzed varieties are all of the same chemical type. 
The differences in the proportion between soda and potash, in 
