THE BASIC MASSIVE ROCKS, ETC. II 
have been seen, and in these the structure is slightly different 
from that of the typical granulitic rocks. The plagioclase in 
them is more or less lath-shaped and the augite grains in many 
cases possess idiomorphic outlines. In section-M. 458 H. for 
instance, the pyroxene occurs in two forms, viz., in small fresh, 
greenish, partly idiomorphic grains that produce with the small 
more or less lath-shaped grains of plagioclase a granulitic aggre- 
gate, and in large altered crystals, filled with magnetite. The 
Fic. 3.—Idiomorphic pyroxene in granulitic gabbro, surrounded by granulitized 
augite. M. 458 H. x. 30. 
outlines of many of these larger grains are clearly the result of 
the crystallizing force, but, nevertheless, they are not sharply 
defined, since their peripheries are slightly granulated (Fig. 3). 
Within the granulated portion, however, the original contours of 
the crystals remain, so that the granulated peripheries are not 
properly granulated portions of the original crystals, as in the 
cases described by Professor Judd,* but are rather additions 
made by small grains adhering to the exteriors of the large crys- 
tals. In the Scottish occurrence the interiors of the grains did 
not assume a definite crystallographic form before the granulated 
pyroxene was produced. Here the homogeneous nucleus passes 
gradually into the granulitic portion in consequence of ‘Crys- 
tallization having gone onto a certain extent, while the | rock | mass 
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