' 
26 | Pentti Eskola. = 6 NTE 
of biotite. In the porphyritic granite of the great batholith 
these dikes are sharply defined, and in the migmatite area 
they appear in the manner of true fissure-dikes independent 
of the strike. The dikes also cut the intrusive granitic por- 
tions of the migmatites, a fact indicating them to be the = — 
youngest intrusions. At places, however, there are still 
younger dikes of melanocratic rocks. . E 
For illustrating the chemical composition of the granite- SO 
aplite, I executed a chemical analysis on a specimen collected 
from one kilometer northwest of Mys Besimyanniy. The SS 
dike cuts the porphyritic granodiorite which in this tract SN 
is typical and homogeneous. It is a dike-breccia, blocks of SM G 
a melanocratic rock being enclosed in the aplite. The analysis = 
gave the following results: i | Sd 
| | JA Mol. Mol. NIO 
numb Yo 
| 
SiO, 73.89 TS CEO: SANS ÖT LTA Ts vios tele Ta ES så 28.62 
Al,O, | 13.37 | 131| 8.51 | Orthoclase....... 37.25 
Fe,O, | 0.57 4 ATDIEC Na csr es SSR JA 26.20 
FeO 1.22 IN 1.69 | Anorthite ...... - 3.89) 
MnO |: 0.05 if | Z sal 95.96 : 
"| MgO. | 0.41 10 | 0.65 CaSiO, 0.46 SR | 
ICaO NE kas 21 |. 1.36 | Diopside. . .2 MgSiO, 0.20 cl TR 
Na,O | 3.14 50 | 3.25 Så FeSiO, ja P=278) 
K,0 6.261 GH ASO LA RR SN ; 
Hypersthene , 1.86 
TION SANN ONS i FeSiO, 1.06 i 
P,O, 0.12 TG Magnetite ....... a RN i 
H,0 0.33 TImenitej. see 0.46 + 
Ål paliter. ovalt AR 0.34 A — 0.34 
2 fem 4.51 6 
. 100.47 
| 100.87 | | 100-00 | 
Liparose (1, 4, 1, 3). 
The Osann figures: ; | NH 
S A C F a c FA NR 
80.18.) 7:61 ,0.907,:1:2.807 13.5 15N SO em 1.0 
