130 B. K. EMERSON — PLUMOSE DIABASE AND PALAGONITE 



Figure 3. — Holvokeite ground of the coarse porphyritic diabase (X 32, polarized 

 "light). 



Showing its peculiar radiate hyalopilitic texture. The larger needles 

 contain a dark central thread of glass (see page 106). 



Figure 4. — Material from a holyokeite dike (X 32, polarized light). 



Showing the same fine hyalopilitic texture as in figure 3. Man}' 

 albite needles penetrate the large glass portion on the right and 

 show a central thread of glass (see page 106). 



Plate 31. — Material from a Composite Dike (X i) 



This material consists of basic diabase aphanite (c), plumose diabase (d), holy- 

 okeite (e), and quartz (b) in normal diabase (a) (see page 108). 



Plate 32. — Graphic Representations of the Constituents of the normal Holyoke Diabase 

 and the extreme differentiation Products ; the Palagonite and Holyokeite 



The method employed is that of Brogger as modified by Hobbs (see page 117). 



