136 
Sodalite occurs abundantly though in varying amount in 
the different specimens of the rock. Sometimes it is in dode- 
cahedra enclosed in felspar crystals; more often it is allotrio- 
morphic towards the felspar but at the same time idiomorphic 
where it borders upon the eudialyte or the dark-coloured 
minerals; in other cases, again, it is interstitial. Between 
crossed nicols it proves perfectly isotropic. It is always sprinkled 
with a large number of minute short prisms of ægirine and 
arfvedsonite; these as a rule show a zonary arrangement paral- 
lel to the dodecahedral faces. Rounded fluid-pores with a 
mobile bubble are also found. In most specimens the sodalite 
is partially altered, especially at the outer border or along the 
cracks; the alteration-product is in some cases analcime in 
others natrolite (spreustein)!. 
Nepheline also occurs rather abundantly. It often fills an- 
gular interspaces between the felspar tables and never shows 
crystallographic boundaries when it borders upon this mineral. 
As a rule it is also allotriomorphic towards the eudialyte, but 
it is idiomorphic towards ægirine and ainigmatite. Towards 
sodalite it behaves in a varying manner: in many cases it en- 
closes crystals or rounded grains of primary sodalite but within 
the same specimens instances of the reverse may also be ob- 
served. In contradistinction to felspar and sodalite the nephe- 
line is very poor in ægirine microlites. Alterations to zeolitic 
matter are common; sometimes also the nepheline is of a cloudy 
appearance, probably in consequence of ordinary weathering. 
Eudialyte occurs in greatly varying amount. As a rule it 
is fresh, showing distinct double refraction. Locally it has been 
converted into an aggregate of catapleiite and light green ægi- 
rine. This alteration has not the character of a resorption 
process, for the original outlines of the eudialyte have been 
1 For a fuller description of the alteration-processes of the sodalite of 
this rock and of the naujaite, see ‘Meddelelser om Grenland' XIV, р. 135 
(1894). 
