Igneous Rocks of Rossland. — B. C. Barber. 337 
crystals are primary, contain inclusions of plagioclase, and 
have a distinct prismatic cleavage of about 124° ; they have a 
maximum length of 2.5 mm., and a maximum width of .4 mm. 
In the network of crystals forming the ground mass, aside 
from biotitc and feldspar, are small crystals of magnetite and 
pyrite, needles of apatite, and calcite and chlorite as weathering 
products. 
Two dark, fine grained kersantyte dikes (6, 34, and 107 
Rossland) were seen; one two feet wide occurs at the 800 foot 
level and the other eleven feet wide occurs at the 700 foot level 
of the War Eagle mine. 
Thin sections, Fig. 2, show a fine grained holocrystalline 
structure containing more biotite than the preceding rock, but 
the crystals are mvich finer grained, A large amount of mag- 
netite is present, and the feldspars are not so clear as in the 
Josie dike, but arc badly kaolinized. 
Camptonytc. — This type of rock (112 Rossland) is a lamp- 
rophyre occurring in a small dike at the 900 foot level in the 
War Eagle mine. It is a medium fine-grained rock, having 
hornblende as the preponderant consituent ; it contains feldspar, 
which is chiefly plagioclase, calcite, chlorite, biotite, and some 
nepheline. 
In thin sections the hornblende is seen to be both primary 
and secondary, and exhibits strong pleochroism from light to 
dark green ; its maximum size is .6 mm. in length and .25 mm. 
in width. The secondary hornblende, uralite, has been altered 
from primary diopside, almost all of which has been changed 
to hornblende. 
The feldspar is chiefly plagioclase with a few crystals of 
orthoclase. the plagioclase being principally labradorite, with 
polysynthetic twinning after the albite law. 
They are generally lath-shaped and some exhibit zonal 
structure ; they have a maximum length of .4 mm. and a max- 
imum width of .2 mm. ; a few, which are probably oligoclase, 
have small extinction angles and little or no polysynthetic 
twinning. 
There is a small amount of magnetite in these rocks and 
some pyrite. Biotite is present in small quantities and shows 
its distinct form and strong pleochroism. 
