1241 
more basic and more acid lamellae are very frequent, and sometimes 
are found repeated several times in one and the same crystal. 
‘ Phenocrysts of the dark minerals are not met with as such, but 
sometimes we find specks consisting of opaque secondary minerals 
proving by their shape that such phenocrysts may originally have 
been present. The groundmass is likewise strongly weathered and 
contains laths of plagioclase, flakes of chlorite and opaque products 
of disintegration of the ore which is not found in large quantity ; 
moreover often an isotropic substance is found in large quantities, 
which is considered as glass; in this case the rock must be called 
an andesite. 
Metamorphosis. 
The metamorphosis of the enclosures examined encludes in the first 
place the alterations caused by the magma itself, appearing only at 
the immediate contact, and consisting, at the utmost, of remelting 
and reerystallisation after chemical exchange; in the second place 
the alterations caused by imbibition of volatile substances which 
penetrate well into the interior of the enclosures. From this the 
intermediary place becomes apparent, which this contactmetamorphosis 
occupies between that of the basaltic and that of the trachytic rocks. 
Especially the intensity of the pneumatolytie influences varies greatly 
in the different enclosures ; sometimes the chemical exchanges in the 
contactzone can be explained without pneumatolysis. In the examined 
rocks it is most frequently the case that in part of the enclosures 
a porous structure has been developed even to a great distance from 
the contact, whilst in the cavities neogenic minerals have been formed 
showing great analogy to the autopneumatolytic minerals of the 
enclosing leucitite, whilst in the contact zone the combined effect of 
remelting and pneumatolysis can be observed. The formation of a 
gold-yellow aegirine-augite is characteristic. 
As an example may serve an enclosure of a few centimeters in 
diameter in which to a great distance from the contact a neogenic 
yellow pyroxene is formed in very small columns, sometimes accu- 
mulating locally and then accompanied by an isotropic mineral with 
low index of refraction and by neogenic feldspar. The angles of 
extinction of this yellow pyroxene point to aegirine-augites of varying 
composition. The ore is strongly disintegrated, here and there a 
reddish substance has been formed pointing to an oxydation to hae- 
matite. A small quantity of the yellow pyroxene is also found in 
the phenocrysts of plagioclase. The transition-zone with the leucitites 
