, A N:o 1) Igneous Rocks of Sviatoy Noss in Transbaikalia. 19 
earlier and then been resorbed. This appears from the follow- 
ing facts: Enclosed in the hornblende are frequent ragged 
remnants of diopside, and all around the crystals there occur 
grains of magnetite, titanite and epidote. The diopside 
apparently. represents the original material and the others 
are second-hand products of the formation of the hornblende. 
Still there are ragged crystals of biotite, enclosed in the 
feldspar as well as in the hornblende and apparently of an 
earlier date than the latter. 
Biotite and diopside were the mafic minerals earlier than 
the hornblende and for greater part now resorbed. But it 
is quite probable that there had been still earlier crystalliza- 
tions, perhaps olivine. Some aggregates of hornblende met 
with in dark segregations in the granodiorite may in fact be 
interpreted as pseudomorphs after olivine, their contours 
agreeing fairly well with the most common crystalline forms 
of that mineral. 
We have here an example of neon and destruction 
of minerals at the magmatic stage, occurring in a rock which 
never was disturbed by movements, neither during nor after 
its consolidation. Similar phenomena have often been met 
Wwith in less well preserved rocks and have there usually been 
attributed to later agencies. It seems to me, that the results 
arrived at in this case may be generalized widely. This is 
also in fair agreement with many results won in the later 
years by experimental physicochemical work. 
The granodiorite of »Camp Mountain» forms a large mass. 
3 A quaternary glacier has worked out a glacial cirque in this 
remarkable rock, and boulders of it, transported by the ice, 
are widely spread around the springs of the Bargousin river. 
In the marginal zone the granodiorite grades into quartz- 
diorite showing similar magmatic resorption of the earlier 
diopside as the granodiorite. - 
A microscopic investigation of the specimens collected 
from the surroundings of the Tshivirkouy Bay, in numerous 
— cases, established an almost the same mineral composition 
as the analyzed rocks. The composition of the plagioclase 
here varies between narrow limits, from about 74 to 78 percent 
