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46 | Pentti Eskola. (LSI 5 
As to the distribution of these two principal kinds it | 
was only stated that the rocks of the actual outcrops a d 
belong to the second group except a few examples from 
point 51 A which all show megascopically an indistinet = 
porphyritic development. In this exposure the börphyriteg . 
variety forms something like an older portion of the rock - 
in which the non-porphyritic portions appear as numerous 
confused primary veins. | 
Examples of the first group were found very copiously 4 
and in numerous structural and mineral varieties in the SS 
shore-drift north of point 47 A and near Markova. 2 
Considering the usual and typical structures of these 
two groups of the andradite-syenites one of them could be 2 
called porphyritic and the other aplitic sviatonossite. These 
names do not emphasize the difference appearing in the 
composition of their plagioclase, indicating a different degree 
of alkalinity. But as this difference is slight and does not 
seem to have any great importance, we shall not choose any 
special names designating these characters. ; 
Porphyritic sviatonossite. 
For closer investigation of the porphyritic sviatonossite 
and its minerals I selected a block from the Baikal-beach 
near point 47 A. It is porphyritic with white and somewhat 
rounded phenocrysts of microperthite and a medium-grained = 
ground-mass in which the andradite forms somewhat larger - 
crystals than the pyroxene. 
The greater part of the block was crushed in a diamond 
mortar. A minor part of this was finally ground fine to serve É 
as material for the rock-analysis. From the larger portion 
I picked up grains of garnet and pyroxene. Much care was 4 
taken to be sure that the garnet portion did not contain any : 
pyroxene and vice versa. The separated portions were then 
crushed up to form a finer powder which was made uniform - oo 
by sifting and washing. Then the samples were treated with 4 
methylene iodide in order to be freed from adhering feldspar ; v 
