e 
550 Reviews—Hruptive Rocks of the Kristiania Region. 
(5) Rocks of the Tvertasite-Fenile series. 
These rocks form a probably continuous rock-series, consisting 
of green pyroxene and alkali-felspar (albite and microperthite). 
The melanocratic member is tveitasite, and the leucocratic type is 
fenite, The fenites are accompanied by corresponding dyke rocks. 
(4) Nepheline-syenite-rocks. 
Quite sparingly distributed is a peculiar type of potash-rich 
nepheline-syenites, including the new type juvite (6°67 per cent 
Na,O, and 8°21 per cent K,O). This is a medium-grained rock 
consisting of orthoclase, pseudomorphs of muscovite and cancrinite 
after nepheline, aegirine, and sparingly biotite. A varietal type is 
described as biotite-juvite. The melanocratic malignite is also 
developed. The new rock-type kamperite may conveniently be 
included here. This rock consists essentially of orthoclase, albite, 
and biotite. It is a perpotassic type (10°16 per cent K,0), and the 
analysis corresponds closely to that of the leucite-basalt of Gaussberg, 
Antarctica. 
(5) Carbonate-rich rocks. 
(a) Sévite—A magmatic carbonate-rock consisting essentially of 
calcite, with apatite, microlite, biotite, and manganophyllite micas 
as important accessories. 
( carbonate-rock (MgCO, 
17:47 per cent, FeCO; 9°60 per cent), associated with apatite, barite, 
and magnetite. In the normal Paubausire, microlite and manga- 
nophyllite do not occur. 
Apart from large masses of these types, independent dykes of 
sévite and rauhaugite are developed cutting fenite, etc. The 
rauhaugite dykes are apatite-rich dolomites (MgO 17 per cent, 
CaO 31 per cent, P.O; 2 per cent. 
(c) Mixed Rocks. nhac which must be regarded as mixtures of 
carbonate magma of sévite type, and of the silicate rocks already 
enumerated are developed as schlieric intrusions, or as dykes 
cutting other members of the Fen group. These mixed rocks 
include hollaite and kasenite, considered as crystallized products 
of a mixture of calcite magma and ijolite-melteigite magma, the 
former relatively rich in silicates (pyroxene, nepheline pseudo- 
morphs, melanite, etc.), and the latter with a relatively . small 
content of silicate minerals ; further, ringite, a type resulting from 
a mixture of calcite magma with a fenite magma constituted of 
calcite, felspar, aegirine and aegirine-diopside, and apatite. 
(6) Damkjernite-sannaite rocks 
An alnéite-like rock which Brégger regards as the latest product 
in the intrusive sequence of the Fen region is described as 
damkjernite. These rocks are melanocratic members of the alndite 
group, and show some variety in composition. The normal type 
contains large phenocrysts of black biotite, and less commonly 
