274 
light coloured constituents: nepheline, sodalite, analcime, and 
small quantities of cancrinite and fluorite. They are all in very 
small grains or anhedra which are interstitial between the fel- 
spar laths. 
The principal ferromagnesian mineral of the ground mass 
is a green biotite in scales or shreds averaging 0/2 millimeter 
in length. They are strongly pleochroic with absorption- tints 
varying from dark green to light yellow. A light green egirine 
in imperfect prisms and rounded grains occurs in varying 
quantities. A colourless or light yellowish-green mineral with 
the same refractive power as ægirine, but differing in Из being 
optically isotropic, is probably garnet. It occurs rather abun- 
dantly in groups of very small rounded grains sometimes show- 
ing roughly hexagonal contours. Iron ore is present in minute 
crystals and grains. Apatite is rare. 
Chemical composition. — The chemical analysis of this type 
is shown in the first column (No. 27) of the table on the next 
page. In the same table the composition of the following type 
(No. 28) is also given. Both agree rather closely and are near 
related to the nepheline-syenite of Korok (analysis No. 25, p. 
235). The same chemical type is rather common among the 
nepheline-porphyries and tinguaites from foreign localities. As 
examples are cited the analysis of a nepheline-porphyry from 
Predazzo and of a tinguaite from the Christiania district. 
Nepheline-porphyry: Nuk type. 
A nepheline-porphyry of a somewhat differing type has 
been found at Akuliarusek on the peninsula south of Fox Bay. 
This dyke strikes N. 35° E. Its width is 13 meters. It is a 
composite dyke, i.e. the middle portion is about 5 meters wide, 
and is flanked on either side by a sharply defined marginal 
zone of a somewhat different character. 
Central part of the dyke. — The rock which makes up 
the central part of the dyke shows some resemblance to the 
