216 
Analyses of porphyrite of Tasek and related rocks. 
22 A B 
SIO Soom shear 47:79 46°10 52.78 
MOS Re Re 3°82 3°34 1°50 
AO Re 16°88 18°59 19:08 
ео еее 4°66 2°63 3°63 
MEO mse. cee 5392 6:68 3°79 
MO PTS chy? trace ‘05 trace 
Мое. ПОЗУ 3:23 1°58 
Г tetas 5°58 9°86 5:09 
NEO rente 176 6:22 7:95 
КО Sr see 3°26 ‘63 3°85 
H,O above 110°.. РЯ "80 | ry 
H,O at 110°.... 14 "11 | 
о попе попе "33 
О eee 16 1°41 ‘63 
COPA ELLE none none ‘10 
Total 99225 99°65 100°75 
Sp. gr 29321 2°895 
22. Porphyrite (trachydolerite), Tasek, Narsak, South Greenland. 
С. Winræer, analyst. 
A. Essexite, Narsak, South Greenland (analysis No. 18, p. 208). 
В. Trachydolerite (lava) Meru, East Africa. В. Mavritz, analyst 
Tschermak’s petrogr. u. mineralog. Mitteilungen XXVII, 1908, 
D322). 
of the needles no birefringence can be detected. Perhaps they 
may be actinolite. The green biotite, which quantitatively is the 
mineral next in importance to the felspar in the ground-mass, 
forms irregular scales seldom more than 0:1 millimeter, the ab- 
sorption-tints for 6 and c are grayish-green or brownish-green 
