8 
BULLETIN OF THE LABORATORIES 
also contains small brownish crystals, that might be taken for garnets, 
but are simply colored augite. There also passes across this specimen a 
small greenish segregation vein. Microscopically, the specimen presents 
a field in which quartz and orthoclase are abundant, considerable biot- 
ite, epidote, some cal cite, augite, hornblende, a little muscovite, oli- 
goclase, magnetite, and a few scales of hematite. Thebiotiteis in both 
long and short crystals. The epidote is in slender irregular crystals of 
a greenish yellow color, in some instances showing paramorphic alter- 
ation from hornblende. One peculiarity of this granite is the presence 
and abundance of augite in association with orthoclase, which is a rare 
thing; but here the numbers of augite crystals are surprising. It var- 
ies from brown to pale brown in color. The other phase of this rock, 
as has been said, is of a lighter shade, somewhat speckeled and of 
coarser crystaline structure, with some of the constituents distinguish- 
able by the unaided eye. Microscopically, the section shows quartz 
and orthoclase in considerable quantity. Biotite is present, and in 
some cases shows pseudomorphic alteration from hornblende. Mus- 
covite is more abundant than in the former, in irregular grains, with 
hornblende, calcite, and a little magnetite. 
The three following rocks studied, are different phases of the 
schist of this region and present a very interesting problem on account 
of the topographical and lithological evidence they furnish of the grad- 
ual alteration from actinolite schist through the various other varieties 
of schist to the pure steatite or soapstone. There is a quarry of this 
soapstone, about two miles from the dyke, and its merchantile value 
gives it at once a leading place in interest. 
The first rock studied is a schist taken at some distance from the 
soapstone. To the unaided eye it is dark green in color with fine felt- 
ing of crystalline rods, and harsh gritty touch. Under the microscope 
it presents a field of actinolite-honblende, very beautiful either with or 
without the polarizer, on account of the distinct outline of the crystals, 
many of which have a beautiful yellowish green border. Some of the 
crystals of hornblende are partly altered to tremolite as in Fig. 5, Sec. 
B, showing the green of the hornblende (h) and white of the tremolite (t) 
in different parts of the same crystal; the alteration is incomplete. All 
stages of transition from actinolite to tremolite are observable. Others 
have made a further change and are taking on the fibrous structure of 
talc. The rock is an actinolite-schist with tremolite, a little magnetite 
