it is not possible to
conceive any other way in which those two substances, quartz and
feld-spar, could be thus concreted, except by congelation from a fluid
state, in which they had been mixed.

There is one thing more to be observed with regard to this curious
species of granite. It is the different order or arrangement of the
crystallization or internal structure of the feld-spar ground, in two
contiguous parts of the same mass. This is to be perceived in the
polished surface of the stone, by means of the reflection of light.

There is a certain direction in which, viewing the stone, when the light
falls with a proper obliquity, we see a luminous reflection from the
internal parts of the stone. This arises from the reflecting surfaces
of the sparry structure or minute cracks, all turned in one direction,
consequently, giving that luminous appearance only in one point of view.

Now, all the parts of the stone in which the figured quartz is directed
in the same manner, or regularly placed in relation to each other,
present that shining appearance to the eye at one time, or in the same
point of direction. But there are parts of the mass, which, though
immediately contiguous and properly continuous, have a different
disposition of the figured quartz; and these two distinguished masses,
in the same surface of the polished stone, give to the eye their shining
appearance in very different directions. Fig. 3. shows two of those
figured and shining masses, in the same plane or polished surface.

It must be evident, that, as the crystallization of the sparry structure
is the figuring cause of the quartz bodies, there must be observed a
certain correspondency between those two things, the alinement (if I may
be allowed the expression) of the quartz, and the shining of the sparry
ground. It must also appear, that at the time of congelation of the
fluid spar, those two contiguous portions had been differently disposed
in the crystallization of their substance. This is an observation which
I have had frequent opportunities of making, with respect to masses of
calcareous spar.

Upon the whole, therefore, whether we shall consider granite as a
stratum or as an irregular mass, whether as a collection of several
materials, or as the separation of substances which had been mixed,
there is sufficient evidence of this body having been consolidated by
means of fusion, and in no other manner.

We are thus led to suppose, that the pow