28 DT SOO LINALTES OF NGL OL OGNE 
The above description will apply on the whole to the horn- 
blende-andesites from the other localities, though in these last 
the phenocrysts are much more abundant. In two of the speci- 
mens, from Mt. Dendros and from the ridge southwest of 
the monastery, the groundmass is markedly spherulitic. The 
spherulites belong to Vogelsang’s globospherites, being rounded 
aggregations of brownish dusty globulites and some trichites, 
arranged so as to give to the spherulite a fine radially fibrous 
structure. Surrounding this fibrous granular center, which has 
no action on polarized light, is a narrow border of clear, colorless 
isotropic glass substance. The groundmass of these spherulitic 
andesites is very vitreous, and with many perlitic cracks. 
Liotite- Hornblende-Andesite. 
group is the rock which forms the small promontory on which 
The only representative of this 
stands the town of Poros. Megascopically the specimens resemble 
much more the lighter hornblende-augite-andesites than the rocks 
just described, having a fine-grained gray groundmass containing 
very many plagioclase crystals and small hornblende needles. 
In this—generally arranged in lines of flow—are very numer- 
ous phenocrysts, chiefly of white plagioclase with stout black 
hornblende prisms and many biotite tables; grains of quartz are 
very rare. Much of the rock is partially decomposed and then 
assumes a reddish brown color, the plagioclase being tinged with 
yellow, and the biotite tables acquiring a brilliant submetallic 
bronze-luster resembling that of phlogopite. 
Under the microscope they show a groundmass of largely 
preponderating colorless glass base, containing many small micro- 
lites chiefly of plagioclase, with plagioclase lathes, small, fresh, 
greenish brown hornblende crystals and but little magnetite 
Flow structure is beautifully developed in the groundmass, and 
segregations are quite frequent. 
The phenocrysts of hornblende are of the same greenish 
brown color and perfectly unaltered; in the decomposed speci- 
mens however being decidedly brown, with no traces of a green 
tone, but still remaining perfectly clear. Biotite crystals are 
quite common, of an olive-green color when unaltered, but in the 
