706 REGINALD ALDWORTH DALY 
Within are embedded the lustrous phenocrysts which generally, 
though not always, lie in the foliation plane when the rock has 
the plane-parallel structure. 
The phenocrysts are glassy to opaque white and seem to be 
in every case either orthoclase or microcline, which may be inter- 
grown with another (triclinic) feldspar in the usual microper- 
thitic fashion. The largest ones are as much as twelve centi- 
meters long. The usual habit is that of simple Carlsbad twins. 
They present straight edges to the surrounding matrix, giving the 
planes (001) (O10) (110) and (101). This idiomorphic appear- 
ance is often lost in the slide through the great amount of resorp- 
tion and marginal corrosion. Occasionally small shreds of biotite, 
a minute individual of apatite, or a few grains of quartz may 
appear in the core of the feldspar, but as a rule it is notably free 
from primary inclusions. The results of decomposition are nor- 
mal. The changing to a reddish hue is common in some weath- 
ered phases. 
The matrix of the rock is simply a typical coarse granitite 
on the one hand or a granite proper (in the classification of 
Rosenbusch) on the other, in either case with or without the 
foliated structure. The feldspars have the same general charac- 
ters as those of the earlier generation except that a triclinic 
feldspar, probably andesine, now appears as an independent con- 
stituent. Quartz, biotite and muscovite constitute the other 
essentials. Large but relatively few individuals of magnetite, 
titanite, apatite and zircon are accessory. The quartz and feld- 
spars are roughly equidimensional with diameters becoming as 
much as a centimeter in length; in fact the feldspars are often 
transitional into the phenocrysts. Quartz very often crystallized 
simultaneously with the feldspars resulting in the formation of 
a true micropegmatite which is extremely common in slides of 
the granite from all the areas. It is best shown in specimens 
collected along the railroad from Hinsdale to Ashuelot. There 
can be little doubt that the structure is primary in the formation 
as a whole. It is possible, however, that in zones of stress 
the development of the structure has been aided by the meta- 
