448 DR. BUNDJIRO KOTO ON SOME JAPANESE ROCKS. 
enclosures with spontaneously moving bubbles. Augite and felspar, 
the latter with liquid-enclosures, are porphyritically imbedded in the 
ground-mass. Dark brown apatite is present. 
The occurrence of rhombic pyroxene in augite-andesites seems to 
berare. Hussak* found near Wiedena (east of Rohitsch) in southern 
Styria an andesite containing, besides monoclinic pyroxene, a mineral 
which is doubtless bastite. W. Cross} has mentioned the andesite 
from Buffalo Peak in Colorado as containing a rhombic augite which 
he considers to be hypersthene. A. Hague and J. P. Iddings = 
have also found hypersthene-andesite at Lassen’s Peak and Rainier, 
besides olivine-bearing hypersthene-andesites and hornblende- 
bearing hypersthene-andesite. Lagorio § found a rhombic pyroxene 
in certain andesites from the Caucasus. F. Becke||, A. Wichmann 4, 
and J. J. Harris Teall ** describe a few other occurrences. 
QuUARTZIFEROUS AUGITE-ANDESITES. 
Quartz-augite-andesites are rare. ‘Tschermak has mentioned one 
occurrence in Caucasia tT. Dolter tt has cited a few localities in 
Hungary, and Hopfner §$ in the rock from the Monte Tajumba in 
Peru. Tschermak is of opinion that here the quartz must have been 
formed before the solidification of the rock. The so-called quartzi- 
ferous augite-andesite from the Andes|||| was afterwards proved to be 
false, although it contains 63-67 per cent. of silica, for no trace of 
quartz has been detected in thin slices of this rock. The high 
amount of silica must in this case be ascribed to its existence in the 
glass-basis in a latent state. I will here mention a few real occur- 
rences of this rock. 
The typical rock occurs in Hosio near the Arafune peak@[Q. Itis 
pitch-black in colour and has a resinous lustre ; felspar (0-3 millim.) 
and augite are porphyritically imbedded in the ground-mass. Under 
the microscope the felspar and augite are generally seen to be rich 
in glass-enclosures and are irregularly bent and cracked. Quartz 
occurs in isolated patches in a rounded form and contains air-pores and 
glass-enclosures, the presence of which and their similarity to those . 
in the felspar are strong arguments that the quartz is a primitive 
constituent of the rock. Tridymite occurs as usual in hexagonal 
scales, the aggregations of which form the lumps around which the 
felspar and augite-microliths assemble, showing at the same 
time a microfluctuation-structure. The tridymite appears to be a 
Neues Jahrb. f. Mineralogie (1880), i. 290. 
Bulletin of the United States Geological Survey, No. i. 1883. 
¢ American Journal of Science, vol. xxvi. September 1883. 
§ A. Lagorio, ‘ Die Andesite des Kaukasus,’ Dorpat, 1878, pp. 18, 85. 
| Tschermak’s ‘ Min. u. petr. Mittheilungen, Band v. p. 526. 
«| bid. p. 38. xx Loe. cit. 
tt ‘ Rosenbusch, ‘ Physiographie,’ Band ii. p. 4138. 
tt Lbid. p. 415: 
§§ Neues Jahrb. f. Mineralogie &c. (1881), ii. p. 164. 
|||| Zirkel, ‘Die mikroskopische Beschaffenheit der Minineralien u. Gesteine,’ 
413. 
“| In the province of Kozuke. . 
K 
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a 
