194 Canadian Record of Science. 
strongly. The appearance was very suggestive of the deri- 
vation of the scapolite from plagioclase, and if this be the 
case the twinning structure of the latter is retained after 
the mineral has apparently been entirely changed tu sca- 
polite. Probably, however, in these cases the change may 
not be complete, and although the mineral has the charac. 
ters of scapolite, there may be sufficient plagioclase remain- 
ing in twinning position to cause the alternate oblique 
extinction observed. There are in the scapolite, inclusions 
of a dusty, opaque character, besides fluid inclusions and 
microlites. The dust and fluid exclusions are disposed 
either in planes or irregularly; in the latter case, the 
section may be really parallel to the planes in which the 
inclusions lie. The microlites lie for the most part in 
cleavage lines, and have their long axes either perpen- 
dicular or oblique to certain planes (sometimes cracks) 
which cross the cleavages. In some instances, numerous 
opaque, thick plates and stout rods were observed lying 
parallel to the cleavage lines. When seen on edge, these 
plates and rods had rectangular outlines, although rounded 
patches of the same opaque material could sometimes be 
seen. Occasionally the scapolite is somewhat cloudy, 
owing to the presence of a kaolin-like decomposition pro- 
duct, but generally it is quite fresh and clear. The epidote 
occurs in small, nearly colourless grains of irregular shape. 
Scattered through both the hornblende and the pyroxene, 
and occasionally to be observed in larger grains situated 
between those of the other constituents, there are irregu- 
larly rounded or oval grains of a mineral which is referred 
to the rhombic pyroxenes. It is biaxial, possesses a rather 
high index of retraction, and polarizes in brilliant though 
somewhat subdued tints. It has one well-marked cleavage, 
to which the extinction is parallel, and has a fine, fibrous 
structure, also parallel to the cleavage, which seems to be 
due to decomposition. The mineral is not quite colourless, 
but has a faint purplish or amythestine tint, and occasion- 
ally seems to be slightly pleochroic. Pyrrhotite occurs very 
sparingly, and is distinguished by its opacity and its bronze 
