No. 200.] 
221 
ceive a distinct denomination, and as it is essentially composed of the 
two minerals already mentioned, so it may receive its name from the 
Hypersthene, as it expresses more significantly its true char^icter. As 
I have placed this among the granites, it would be unnecessary to state 
that it is an unstratified rock, were it not that some geologists place 
gneiss among them also; calling it by way of distinction a stratified gra- 
nite. Though it is a formation thus distinct, mineralogically considered, 
still it passes into gneiss, and other primary rocks which are adjacent to it 
It divides or separates into thick bedded masses, especially towards the 
summits of the higher mountains, where the decomposing agents are far 
more active than on the plains below. The true granites are acted upon in 
the same manner. The colour of the rock is a smoke gray, passing from 
light to dark. It is frequently traversed, by lighter coloured veins, on a 
darker ground, which are more distinctly brought out by polishing. — 
They have an injurious effect, as in those places where these veins ap- 
pear no play of colours can be observed. When viewed at a distance, 
this rock resembles an hornblende rock. It has often a greenish or gray- 
ish purple colour, especially where it is exposed by slides. In a few 
places, it is wholly a greenish compact feldspar. At these localities the 
Hypersthene is wanting, and it loses its beautiful play of colors, so well 
known in the Labrador feldspar. No mica or quartz can be discovered 
in it, except as veins or small insulated beds, evidently having no more 
connection with the rock in the mass, than any other foreign mineral, 
that is, they do not form a part, or a constituent element of it. A more 
constant mineral is the magnetic, or protoxide of iron, small particles of 
which are quite common, and also small amorphous garnets, arranged in 
zigzag lines, surrounding the small masses of iron. The iron and gar- 
net are, however, more common in the immediate neighborhood of the 
heavy beds of iron, and may be considered as indications of their pre- 
sence. In the fresh, solid masses of the rock, or those recently broken 
from the quarry, the Hypersthene resembles so closely hornblende, that 
it may be mistaken for it; but after exposure to the weather, the lami- 
na very slightly separate, and in this state the cleavages and primary 
form of the mineral are readily obtained. The Labradorite constitutes 
by far the largest portion of the rock. Taking the rock in a mass, the 
particles of composition are small, and irregularly mingled together, but 
n^ver occurs in a compact state, unless in the greenish white variety, 
just spoken of. We frequently find, however, large blocks, or imper- 
fect crystals of it embodied in the rock. These always exhibit more or 
less of the play of colours considered as characteristic of the species. — 
It is, however, generally coarse grained, as it would be termed, passing 
