39 
The lujavrites. — The rocks which are called here the 
lujavrites, have in their general habit a good deal in common 
with the typical lujavrites, which we know through W. Ransar's 
work from the Kola Peninsula; the dark-coloured minerals are 
very abundant and have the form of needles or slender prisms, 
and the whole rock has as a rule a well-marked flow-structure 
which produces an apparent schistosity. They are distinct from 
the Kola rocks, in that the size of grain is as a rule smaller 
and the black minerals are more strongly represented. In outer 
appearance they are very different from the ordinary igneous 
Kitdlavat 
1260 m 
Laxe-Elv Laxe-Elv 
w.tribulary E.tributary 
> GL 
N.75°W. S.75°E. 
Granile (algonk) 
kakortokite 
Fig. 5. Section of the nepheline-syenite complex from Laxe Elv to Kitdlavat. 
(continuation of the section Fig. 4). — Scale 1 : 38000. 
rocks and resemble most of all the crystalline schists; the 
few travellers who visited this region in the first half of the 
19 century call the lujavrites “chlorite schists’ or “а kind of 
gneiss”. 
In the chemical composition the main difference between 
the black and the green lujavrite is in the oxidation stage of 
the iron, but their external appearance is very different and 
each may be described separately therefore. 
The black lujavrite — arfvedsonite-lujavrite — is in its 
typical form a moderately fine-grained, grayish-black rock of 
a somewhat schistose structure. The one conspicuous component 
is arfvedsonite; it contains, further, nepheline, microcline, albite 
