128 GCRYSTALINE ROCKS OF N. S. AND C. B.—HONEYMAN. 
tion. The groundmass transmits polarised light with the nicols 
-erossed, and brightens considerably with the turning of the pola- 
riser. Its dichroism shows that one constituent is horablende. 
Crystals interspersed, having median lines and the general 
colours, seem to indicate albite as also a constituent. The red 
crystals which led me to characterize it as porphyrite, are of un- 
certain character, not having any distinguishing feature. The 
amygdules which I consider to be calcite, show a varied and 
beautiful chroism. One or two of these are pervaded by fine 
parallel lines which are sometimes crossed by other parallels. 
The turning of the polariser does not much affect this striation. 
It is not, therefore, of the character of the feldspar striation. 
Some of the amygdules are of a yellow colour; three of these 
are in the section with the nicols crossed ; these are green and 
black, so arranged as to appear to radiate from the centre. 
Turning the polariser half a revolution, they become yellow, 
without the appearance of radiation. The mineral is evidently 
dichroic. J do not know what it is. There are also dark forms 
in the groundmass. (b.) The microscope shows that these are 
magnetite. The constituents of this rock are therefore horn-~ 
blende, albite, calcite, magnetite and (?) mineral. 
10. In the second of the Whetstone Brook sections which 
succeed the Wentworth, I. C. R. is porphyrite which is associated 
with Diorites. The slates which include them have only produced 
one fossil a large lingala. They have been referred doubtfully to 
the middle silurian period. (Vide,) paper already referred to. This 
porphyrite has a dark ground mass in which are scattered reddish 
erystals and kernels of Iryaline quartz. (a.) In section the 
ground mass transmits light with crossnicols and brightens with 
rotation of the polariser, hornblende is evidently one constituent. 
The sections of the reddish erystals are dichroic, the mineral is 
therefore monclinic, orthoclase. One has four different shades of 
eolor (brown,) irregular dividing lines which deepen in different de- 
grees with the rotation of the polariscope, and after half a rotation 
or a little more, becomes white (grey.) #One of these has a distinct 
inclusion (mineral.) The hyaline quartz is of a dark blue when 
the nicols are crossed. The ground mass is unindividualized. (a.) 
