50 
observed here. On the steep, north side of the eastern peak 
of Iviangusat the augite-syenite is seen as a broad zone, which 
even at a distance is very conspicuous with its dark reddish 
brown colour. The boundary towards the granite has here a 
dip of about 70° towards the south-west. On the south side 
of Kangerdluarsuk Fjord both boundaries of the syenite belt are 
exposed; here the boundary planes are vertical and strike from 
east-south-east to west-north-west; the breadth of the augite- 
syenite belt at this place is about 250 meters. 
It will be seen from this, that the augite-syenite in the 
region considered forms a broad, dyke-like mass, whose boundary 
surfaces towards the surrounding rocks are vertical or inclined 
at large angles. The augite-syenite body however has not the 
form of a typical dyke; on Laxefjeld, for example, there are 
three or four smaller portions of the augite-syenite, isolated 
both from one another and from the main body in the valley 
east of Laxefjæld. One of these outliers forms the top of Laxe- 
fjeld (see Fig. 5, р. 39), and they all rest upon the lujavrite 
with more or less horizontal boundaries towards this. 
The augite-syenite. — This rock is of coarse or medium- 
sized grain, and of a whitish gray colour. It consists mainly 
of a white felspar (size of grain about 1—3 millimeters) and is 
irregularly spotted with black minerals in considerable quantities. 
Among these a coal-black augite (with grains up to 6—7 milli- 
meters in diameter) is predominant, and magnetite is relatively 
abundant. With the aid of the lens small yellowish brown grains 
of olivine are frequently seen. None of the constituents show 
a distinct crystal form; the grains are interlaced irregularly. 
It is only seldom and in patches that the felspar is quite fresh; 
it then shows a grayish clear colour with a fine blue schiller. 
A very characteristic feature of this rock is the reddish brown, 
rusty coating, which is seen everywhere on the outer surfaces 
and along the fissures; it is undoubtedly connected with the 
presence of the olivine which is rich in iron and is readily 
