from the Standpoint of Physical Chemistry. 



221 



that while the plagioclase laths are indented by the diopside 

 crystals, the characteristic elongated form of the plagioclase is 

 maintained. 



These phenocrysts of diopside and plagioclase are bordered 

 by dark plumose growths, or hair-like tufts 



fading out at the 



Fig. 1. 



Fig. 1. Typical structure of the vitrophyric phase resulting from quick 

 chill. (Slide No. 105.) Elongated crystals plagioclase, stouter forms diop- 

 side, matrix light-green glass, perfectly isotropic. Actual diameter of 

 field l-5 mm . 



periphery into the surrounding glass. Under the high-power 

 objective they are resolved into innumerable microcrystalline 

 growths, straight or curved, sometimes branching in lattice-like 

 forms, thrown out from the boundaries of the phenocrysts. 

 With the high magnification they exhibit the development 

 sketched in fig. 2. 



Fig. 2. 



Fig. 2. Microlitic growth of plagioclase and diopside, greatly magnified. 



