PRELIMINARY NOTES ON SOME IGNEOUS ROCKS OF 
JAPAN. VIE 
S. KOZU 
Imperial Geological Survey of Japan 
VI. QUARTZ-SYENITE AND COMENDITE FROM THE OKI ISLANDS 
Introduction.—Our geological knowledge of the Oki Islands is 
derived in the first place from the late Dr. T. Harada,’ Mr. B. 
Minari,3 and others, and subsequently from the more detailed 
work of Mr. M. Yamakami.* The last author’s report and geo- 
logical map were published in 1896 by the Imperial Geological 
Survey of Japan, and many rock-specimens collected by him are 
preserved in the Survey collection. Among them, I have found 
some interesting alkalic varieties, many of which have not yet 
been described in Japan; and their occurrence in our country, 
especially near the coast of the sea of Japan, is very interesting from 
a petrological point of view. In the summer of rorz, I had an 
opportunity to visit the islands and to make a collection of several 
varieties of these interesting rocks. The following description is a 
preliminary account of the petrological observations made on my 
journey, and of the quartz-syenite and comendite, the most inter- 
esting rocks that I collected. 
For the chemical analyses of these rocks, meds in the laboratory 
of the Imperial Geological Survey of Japan, I am greatly indebted 
to Mr. K. Yokoyama, and my sincere thanks are due to Professor 
B. Koto, for advice and assistance in the study of the rocks. 
«Published by permission of the Director of the Imperial Geological Survey of 
Japan. 
2T. Harada, Versuch einer geotectonischen Gliederung der japanischen I nseln, 
Imp. Geol. Survey, Japan, 1888; T. Harada, Die japanischen Inseln, Imp. Geol. 
Survey, Japan, 1890. 
3 B. Minari, Explanatory Text to the Agronomic Map of Izumo, Iwami, and Oki 
Provinces (in Japanese), Imp. Geol. Survey, Japan, 1895. 
4M. Yamakami, Explanatory Text to the Special Geological Map of the Section 
Oki (in Japanese), Imp. Geol. Survey, Japan, 1896. 
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