196 Canadian Record of Science. 
eranulitic “ groundmass’” composed chiefly of feldspar 
with some quartz, biotite and hornblende; and (2) a coarser 
grained portion imbedded in this “groundmass,” but not 
having any definite crystalline boundaries. The minerals 
composing this coarser grained portion are scapolite, pla- 
gioclase, biotite, hornblende, and occasionally quartz. A 
gradation between the ‘“ groundmass”’ and the coarser 
constituents can generally be observed, and in some few 
instances there appears to be evidence that the former was 
derived from the latter, particularly from the plagioclase, 
by crushing, the structure being cataclastic. In this con- 
nection, the absence of pyroxene is noteworthy. ‘The sca- 
polite is generally coarsely crystalline, and present in large 
amount. Only occasionally is it sparing in quantity or 
finely crystalline. Very commonly it occurs in large 
plates of uniform orientation, in which more or less elon- 
gated individuals of hornblende or biotite lie irregularly 
imbedded, the structure being quite analogous in appear- 
ance to the ophitic structure seen in diabases. In one 
case, a large plate of scapolite was observed to inclose an 
irregular grain of plagioclase, the latter being somewhat 
decomposed. The scapolite usually occurs side by side 
with plagioclase or with plagioclase and quartz, all being 
in very irregular shaped grains, evidently allotriomorphie. 
The line of contact between the plagioclase and scapolite is 
quite sharp, and generally there is but little evidence of the 
derivation of the latter from the former. Associated with 
the scapolite, there is often a fine-grained aggregate of gray 
decomposition products, which shows aggregate polariza- 
tion in brilliant but subdued colours, and which probably 
consists of muscovite, calcite, etc. 
Hornblende and biotite are well represented in all the 
sections, the former being rather more abundant than the 
latter. The hornblende is of a deep green colour, strongly 
pleochroic, and contains numerous inclusions. The biotite 
is of the usual brown colour, and some grains contain inclu- 
sions, in the shape of films running in between the cleavage 
lamellee, of a mineral which between crossed Nichols resem- 
