164 
Egirine is always very abundant in green needles show- 
ing the usual characters and arranged parallel to the rock. The 
needles are usually from 0°01 up to 0°20 millimeters thick by 
1 or 2 millimeters long. As a rule they are well crystallized 
and bounded by the faces (100) and (110) in the prismatic 
zone; less frequently terminations are seen. The _ needles 
are often found broken or curved round the light coloured 
minerals. 
Arfvedsonite appears in scattered anhedra or prisms of 
relatively large dimensions (1—-3 centimeters) poikilitically en- 
closing a very great number of crystals of felspar, nepheline, 
and eudialyte. In many specimens it has been entirely converted 
into aggregates of acmite-grains or -prisms of the usual kind 
(see р. 137). 
Sodalite as already mentioned is found as an alteration- 
product of nepheline. In a few specimens it has also been 
observed in independent crystals of about the same dimensions 
as the nephelines. The sections of the sodalite-crystals are 
roughly hexagonal though the crystal form is hardly deve- 
loped. 
Analcime is much more abundant in this rock than in 
those previously described. As far as it has been ascertained 
it is always a secondary product replacing the light-coloured 
minerals in the manner described in the preceding pages. The 
amount of analcime present varies within wide limits; of two 
rock-specimens, externally alike and taken in the same place, 
one may prove nearly unaltered while the other has been so 
strongly influenced that analcime replaces almost the entire 
amount of light-coloured minerals. 
In a few cases the analcime occurs in a very peculiar 
manner building large icositetrahedra sometimes attaining 12 
centimeters in diameter and appearing as big knots in the 
schistose rock. The icositetrahedra have been analyzed by Dr. 
Jur. Petersen with the following results: 
