SKETCH OF ASGINA AND METHANA. 39 
very few biotite tables and still more rarely quartz grains. The 
scoriaceous specimens are decomposed and have become rather 
friable and of a dark reddish brown color. The specific gravity 
was found to be 2.44 in the freshest specimen. — 
Microscopically they show a hyalopilitic groundmass of color- 
less glass base with very numerous, almost or quite colorless, 
hypersthene and fewer plagioclase lathes. Larger, but still 
extremely small plagioclase and hornblende crystals, together 
with a few colorless augites, are also present in the groundmass. 
The hornblende which occurs as large phenocrysts is generally 
prismatic, and of a brownish green color, quite fresh and free 
from alteration. It contains some inclusions of magnetite, 
plagioclase and a few biotites of large size and is itself inclosed 
partially by the largest plagioclase phenocrysts. These latter 
which, judging from the extinction angles on c (001) of 35°-38°, 
are anorthite, are quite fresh but contain many inclusions, chiefly 
of brownish glass with bubbles, and in one case of very many 
small flakes of biotite. A few phenocrysts of the latter are also 
seen, and good-sized grains of magnetite are abundant. 
The hornblende-hypersthene-andesites from the other two 
localities much resemble the above, that from the top of Mt. 
Chelona differing chiefly by its more typical hyalopilitic structure, 
the absence of transition forms between the phenocrystic and 
groundmass crystals and the more vivid green of the hornblende. 
Flornblende-Dacite—This composes the two hills at Anzeiou 
and Kakoperato in the Oros District on Atgina which seem to be 
later flank eruptions of the main Oros outflow. The Anzeiou 
rock is ight gray, rather compact and quite free from pores but 
rough in feel. The groundmass is fine-grained with numerous 
small hornblende needles. | Phenocrysts are very abundant, 
chiefly white plagioclase crystals with some larger black horn- 
blende prisms and many slightly pink quartz grains, generally 
rounded, but here and there showing a bipyramidal form, unac- 
companied by an augite fringe. 
The Kakoperato rock differs somewhat from the other, the 
phenocrysts which are the same as in the preceding being much 
