197 
Umptekite of Kola (D in the above table) is also of interest as 
this rock appears as part of a rock assosiation similar to the 
Narsak-nordmarkite. 
Contact Facies of Nordmarkite. 
Normal contact facies. — As mentioned in the geological 
section (p. 100) the nordmarkite has a distinctly marked endo- 
morphic contact facies where it borders on the superincumbent 
rocks of the volcanic series. This contact facies may be char- 
aclerized as a nordmarkite-phorphyry containing the same mi- 
neral components as the main type of rock. The phenocrysts 
are felspars consisting chiefly of soda-orthoclase; the angle of 
extinction in sections parallel to (010) is about + 9°. They are 
remarkable by their form which gives a lozenge shaped section 
as in the Norwegian rhomb-porphyries. They are much less 
pure than the felspars in the coarse-grained nordmarkite as they 
enclose small rounded crystals of augite, hornblende and iron- 
ore. The ground-mass consists of soda-orthoclase with per- 
thitically imbedded albite, green hornblende, sometimes also 
a little augite and biotite, further iron-ore and apatite, and 
finally interstitial quartz which is a constant but very subordi- 
nate component. The felspars of the ground-mass have the 
form of laths, seldom more than 0:1 millimeter wide, and the 
structure is a typical trachytoid flow-structure. 
Granitic contact facies. — At the contact with the sand- 
stone on the south coast of Sermilic Fjord (p. 103) the nord- 
markite has dissolved silica from the sandstone, and in a zone, 
one half to one meter wide, nearest the sandstone the rock is 
a medium-grained granite. This contact-rock consists of fel- 
spar and quartz with some egirine, arfvedsonite and ainigmatite. 
The felspar-crystals have a shape giving imperfect tabular sec- 
tions, and consist of microcline-microperthite. The twin struc- 
ture of the microcline is irregularly granular or finely dotted, 
and the perthitic structure is finely lamellar with somewhat 
