Some Canadian Rocks containing Scapolite. 197 
bles scapolite, but which are so minute that their character 
cannot be determined with certainty. The plagioclase is 
usually quite fresh and clear. In the “groundmass,” the 
feldspars are only twinned occasionally and can be distin- 
guished from the quartz only by means of the interference 
figure in convergent polarized light. 
The most striking of the accessory minerals, and at the 
same time the only constantly idiomorphic constituent of 
the rock, is the epidote. It occurs in elongated prisms of 
rhombic cross-section, which vary much in width, in 
some cases forming slender needles, but elsewhere being of’ 
stout columnar habit. The crystals are colourless, but 
between crossed Nichols, polarize in the usual brilliant 
manner. The extinction is parallel to the side of the 
prism that is to the axis, and in cross-sections is oblique to 
both of the crystallographic lines. The plane of the optic 
axes may readily be determined to be perpendicular to B. 
The index of retraction is high, the prisms standing out in 
marked relief, and irregular transverse partings can occa- 
sionally be observed. In one section a large plate of zoisite 
was observed. It was oblong in shape, showed a perfect 
cleavage parallel to its length (« P &), and a distinct cross 
parting. The plane of the optic axes was found to be at 
right angles to the C axis. The mineral is colourless, and 
shows dull gray to deep blue polarization colours, Titanite 
is rare, and occurs in small, rudely wedge-shaped grains. 
The rock may be called a Plagioclase Scapolite Amphibolite. 
The rock from McDougall [Museum Number, 2996,] is 
coarse-grained, and possesses a rather indistinct foliation. 
Under the microscope, it is seen to be a granular aggregate 
of plagioclase, scapolite and green hornblende, with a sparing 
amount of pyroxene and quartz and a little accessory epidote 
and pyrite. The plagioclase is for the most part fresh, though 
occasionally a little cloudy, and by means of Lévy and Pum- 
pelly’s method was found to belong to the anorthite-labra- 
dorite end of the plagioclase series. The plagioclase and 
hornblende are present in about equal proportions, The sca- 
polite is less abundant, and occurs in large, irregular-shaped 
