140 LE JOULNATE ORANGE OLOGY. 
plagioclase crystals, and rather dark gray color which on weath- 
ering becomes a pinkish brown. Exceptions to this general 
structure are found in the segregations of the Kaimeni stream, and 
in one from Mt. Gaiapha, which are much larger grained and look 
like medium-grained diorites. They carry few phenocrysts 
though some are seen in almost all the specimens, in most cases 
of white plagioclase and more rarely of short, black hornblende 
prisms. The Kaimeni segregations also show several clear, color-_ 
less quartz grains with no augite rings, and those from Kakoperato 
some pinkish quartzes of larger size and surrounded by a narrow 
ring of green augite. 
Under the microscope it is seen that the segregations show in 
general the same mineral composition as their enclosing rock, 
except that no quartz was found in the slides, even in those of the 
dacites rich in quartz. We can distinguish in the sixteen specimens 
examined two distinct varieties which differ considerably in struc- 
tural and in mineralogical characters; first with the mineralogical 
composition of hornblende-augite-andesite, which are found in 
the rocks of Mts. Pagoni and Gaiapha and presumably also in those 
of Mt. Chondos, and secondly, hornblende-andesite segregations 
from the andesite of Kaimeni and the dacites of Anzeiou, Kako- 
perato and the neighborhood of Kosona. 
The first variety has a peculiar porphyritic structure of which 
the groundmass is not abundant, and is analogous to the mesos- 
tasis of some melaphyres. It is quite trachytic in appearance, 
being composed of colorless plagioclase lathes and leptomorphic 
grains, with many twinning lamelle, some of which gave extinction 
angles of about 15°. No flow structure was noticed, and inter- 
stitial glass base seems to be entirely wanting in nearly all the 
specimens. In this trachytic paste are many small hornblende 
prisms and needles, all of which are entirely altered to a fine- 
grained mixture of augite and opacite, and many small, colorless 
augite crystals either prismatic and broken or of irregular shape, 
some of which seem to be derived from the large altered horn- 
blende phenocrysts. Magnetite is very rare in these segrega- 
tions. 
