PRELIMINARY NOTES ON SOME IGNEOUS ROCKS 
OF JAPAN*: 
S. KOZU 
Imperial University, Sendai, Japan 
COMENDITE 
This remarkable rock is found as blocks in a small stream run- 
ning into the Bay of Iibi, a small village on the northeastern coast 
of Doégo. The environs of the village consist mainly of schistose 
granitic rock and its porphyries, in association with rhyolites. 
Though the exposure of the comendite was not observed by the 
writer and its geological occurrence cannot be stated at present, it 
seems highly probable that the rock is a differentiated and effusive 
form of the same magma from which the above-mentioned rocks 
were derived. 
Megascopically, the rock is light gray with a bluish tone and 
exhibits a distinct wavy flow structure, produced by the arrange- 
ment of feldspar crystals and lighter-colored crystalline bands, and 
has a tendency to platy parting under the hammer. Numerous 
phenocrysts are quartz and feldspar. The quartz is conspicuous, 
with rounded outline, and varies in diameter from 1 mm. to 3 mm. 
The feldspar is glassy, fairly well defined, and prismatic or tabular, 
from 1mm. to 5 mm. in length, the prevailing length being 2 mm. 
Megascopic phenocrysts of colored minerals are rare. The ground- 
mass shows a certain diversity of texture, some parts being aphanitic 
and compact, and some parts more crystalline and lighter in color. 
This property produces the fluxion structure already mentioned. 
Microscopically, the constituent minerals are quartz, alkali- 
feldspar, arfvedsonite, barkevikite, aegirite, aegirite-augite, titani- 
ferous iron, magnetite, and apatite. The conspicuous pheno- 
* Published by permission of the Director of the Imperial Geological Survey of 
Japan. 
* A continuation of Paper VI, on “Quartz-Syenite and Comendite from the Oki 
Islands,” published in the issue of this Journal for October-November, 1912. 
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