Some Canadian Rocks containing Scapolite. 195 
colour in reflected light. In one instance it was seen to be 
included in the scapolite, which was stained yellowish- 
green in the vicinity of the grain. Other grains occur 
bedded in the hornblende. Rutile occurs in occasional 
grains, rather large in size and irregular in shape, but has 
not been observed in its usual prismatic habit. It has a 
high index of retraction and a faint brownish or reddish 
colour, and resembles titanite very much both in ordinary 
light and between crossed Nichols. In convergent light, 
however, it gives a distinct uniaxial interference figure, and 
there are traces of a quadratic cleavage. It polarizes in dull, 
leaden-gray tints. In two instances these grains of rutile 
were seen to be made up of lamellz, as if polysynthetically 
twinned. There was, however, no alternation of extinc- 
tion corresponding to the alternate lamelle. In a certain 
position between crossed Nichols, the section was broken 
up into these lamelle, which were alternately light and 
dark. On revolving the stage through 90°, the same 
appearance is produced, i.e., the same lamelle are light 
and dark as before, and there is no position in which the 
light lamelle become dark and the dark lamelle light. In 
one of these two instances, the polyxenthetic lamelli 
appeared to cross each other, the angle between the two 
sets being, as nearly as could be measured, 53°. The rutile 
is associated with the scapolite, and in the last-mentioned 
case, where the grain has a diameter of 14 mm., it is 
entirely surrounded by seapolite. In this case the glass 
cover having been removed, the section was treated with 
hydrochloric acid, the mineral, however, was quite unacted 
upon. Following Sjogren, the rock may be termed a 
Scapolite Diorite. 
The rock from Mazinaw Lake [Museum Number 2930| 
is rather coarse-grained and distinctly foliated. The prin- 
cipal constituents are hornblende, biotite, scapolite, plagio- 
clase and, in smaller amount, quartz, The accessory mine- 
rals are epidote, ziosite and titanite. Pyroxene does not 
occur in any of the slides. In nearly all the sections the 
rock is seen to be made up of two parts: (1) a fine-grained, 
