Igneous Rocks of Rossland. — B. C. Barber. 339 
and have a maximum length of 1.4 mm., and a maximum width 
of I. mm., those of the second generation occur only in the 
ground mass, are quite fresh, and have a maximum width of 
.05 mm. 
The feldspar is largely labradorite, having an extinction 
angle varying from 21° to 28° and showing twinning after the 
albite law ; much of the plagioclase is kaolini/.ed ; its maximum 
size is 1.2 mm. in length and .2 mm. in width. Some of the 
plagioclase is altered around the edge to calcitc, while a number 
of crystals which are oligoclase and orthoclase show little or no 
twinning and have nearly parallel extinction. 
Hornblende is present chiefly as an alteration product of the 
augite. The biotite is in various sized crystals up to i mm. 
in length, and the quartz shows corrosion around the edges. 
A small augite camptonyte dike (61 Rossland) was also 
found at the 700 foot level in the War Eagle mine. The rock 
is darker than the preceding, contains less biotite and feldspar, 
and greater abundance of pyroxene, which is diopside instead 
of augite ; the crystals are smaller and the feldspars are not so 
badly kaolinized. 
TRANSITIONAL ROCKS. 
Associated with these rocks which are true kersantytes, or 
camptonytes, are various gradations from one type into the oth- 
er. They are alike in having a ground mass with a basic plag- 
ioclase predominating over the acid feldspars and quartz ; some 
of the camptonytes, however, while having the necessary con- 
stituents, augite and hornblende, have almost an equal amount 
of biotite, which would class them not as camptonytes or ker- 
santytes, but midway between these two types. 
The following is a description of a rock of the camptonyte 
type (25 and 49 Rossland) but containing considerable biotite, 
and yet so near in structure to a diabase that it might well be 
classed as such except that it appears to be too acid for that 
group. It is fine grained and occurs as a two-foot dike in the 
ninety-foot Josie dike, and having the same strike. 
In thin section. Fig. 6, the rock is holocrystalline, with a few 
large lath-shaped plagioclase feldspars and augites that are 
altered into hornblende, embedded in a fine grained crystalline 
groundmass. The groundmass consists chiefly of plagioclase, 
