KEGKACN:o 1) Igneous Rocks of Sviatoy Noss in Transbaikalia. 25 
apatite. Assuming the albite, magnetite and apatite to be 
present in the same amounts as they appear in the norm 
and rating the amount of muscovite approximately, the actual 
mineral composition or mode of this rock may be calculated 
as follows: 
(0 TATE Moss SS SS SIE SM efaae YT Se 24.66 
NIICROCIING 2 stra star NA ge NS 220 
AN TIST GC SS Sätea tafsare LS 40.35 
SAST ORM GCK sar ba Ia NAR 3.89 
| ATOM ESR se SAGA SIR AR SR AD SMS NIA 5.44 
VILSE OMIEE! «eo RER sas LG 0.50 
ECO TATT G Sd sg obs styrs tel Ten ere bre 0.78 
MaOnhel ber ss Esra sees 1530 
TUTTAR SNR EA RIA A ap SA SEE 0.67 
99.92 
About the structure of this rock, little of interest can be 
said. All the minerals are devoid of crystalline forms and 
> their boundaries are ragged or serrated. 
- No perthite is present. The quartz shows very little 
strain shadows. K 
Specimens of the aplitic granites from other localities 
examined microscopically' do not exhibit anything of parti- 
cular interest. The structure is always the same, aplitic. The 
mineral composition is invariably characterized by the pre- 
— valence of alkali feldspars. Orthite with surrounding epidote 
was observed in some specimens. Magnetite is always rather 
— abundant as an accessory. 
The Dike-rocks. 
Alpi iten Dk es: 
Dikes of granite-aplite are met with on Sviatoy Noss 
Wherever rock is exposed. In the even-grained aplitic granite 
= they present the aspect of primary dikes having ill defined . 
: — boundaries and the dike-rock being often nearly identical 
With its country-rock, but containing a little smaller amounts 
