225 
which is quite independent of the presence of the arfvedsonite- 
like needles. 
Chemical composition. — A specimen of the above mentioned 
quartz-porphyry from a dyke 5 meters wide, at a height of 830 
meters, east of the summit of the Ilimausak, has been analyzed by 
Dr. Wintaer. The results have been given in No. 24 of the table 
above. The figures of the analysis and the microscopic charac- 
ters agree in showing that the quartz-porphyry from the Ш- 
mausak belongs to the alkali series and must accordingly, in 
the system of Rosexgusch, be referred to the comendites. For 
comparison an analysis of the comendite from Comende in Sar- 
dinia has been given in A. 
XXXVIII. 15 
