UR 
A N:o 1) Igneous Rocks of Sviatoy Noss in Transbaikalia. 91 
by the magma in which they have sunk, and this resorption 
has worked similarly on the andradite and limestone, a fact 
proving the partial assimilation to have taken place posterior 
to the formation of the skarn from limestone. This is a fact 
of interest for the discussion of the genesis of the andradite- 
syenites. 
The most important contact-phenomena between the 
sviatonossite and its country-rocks may be summarized as 
follows: The sviatonossite is intrusive in the schistose rocks 
of Sviatoy Noss and is geologically connected with the granites 
injected in these. In it are enclosed fragments detached from 
the country-rock, the latter consisting, on the southeastern 
side, of a migmatite of granite and amphibolite. Only frag- 
ments of amphibolite have been observed, but no such of 
granite. On the northwestern side of the sviatonossite-mass 
limestone occurs, at several places, in immediate contact 
with the sviatonossite. In this rock-mass are enclosed frag- 
ments of limestone and andradite skarn, some being only 
rounded by assimilation, while others have been more or less 
perfectly assimilated by the magma. 
As to the other occurrences of sviatonossites near Markova, 
nothing is known about their contact-phenomena. It is only 
certain that syenitic varieties here also grade into granitic 
ones and that limestone, as small lenticular masses, is dis- 
tributed everywhere in this part of the peninsula. 
The Origin of the Sviatonossites. 
After the description of the phenomena observed at the con- 
 tacts and in the enclosed fragments in the andradite-syenite, 
no words are needed to convince the reader that the rock 
owes Its content of andradite to assimilation of limestone or 
its derivatives. Two different suppositions may be inferred: 
either the magma has dissolved limestone, and the andradite 
has crystallized out at the cooling, the carbon dioxide 
emanating at the same time, or the magma has first formed 
andradite-skarn at the walls towards the invaded limestone 
and in the enclosed fragments, and afterwards, having been 
