260 Dr. J. W. Webster on St. Michael 
felspar is divided into prismatic distinct connections, which 
are from half an inch to two inches in length, and from an 
eighth of an inch to an inch in thickness.” The angles and 
‘edges of these masses were rounded and showed marks of 
attrition—Angular spaces have been left between the con- 
cretions, in one of which, says Dr. Webster, I discovered a 
portion: of transparent quartz having a red tint. The spaces 
are partially filled by crystals of hornblende projecting into 
them, anditis probable that they were once entirely oceu- 
pied by that mineral. A small quantity of black mica ad- 
heres to the surface of ‘some of the largest concretions of 
felspar. . 
The most singular cireumstance in these masses, is the 
division of each one of them into a coarse and fine grained 
portion. The latter, composed likewise of hornblende and 
felspar, intimately mixed, and in nearly equal quantities, 
forms a nucleus, which is completely enveloped by the 
coarse concretions. There is no gradual transition from the 
one to the other, but they are so distinct, that, on the ap- 
plication of a slight degree of force, they separate from 
each other, and the nucleus, or fine grained portion, pre- 
sents a smooth and convex surface. ‘The lustre:and trans- 
lucency of the felspar, in all these fragments, is such as 
evinces that they could not have been subjected to a very 
elevated temperature.” ‘The author then goes on to re- 
mark, that “ if these rocks had been found on a mountain, 
composed of the primitive rocks of many geologists they 
_ would have been described as granite, or sienite, and there 
is a Dr. Webster’s opinion, no reason why ‘they are “not, 
in. their present situation, equally entitled to the name.’ 
~ Perhaps we do notexactly apprehend the author’s meaning. 
He evidently does not intend that the specimens resembling 
granite and sienite (and this resemblance has appeared to 
us On inspection of the specimens tobe very striking) indicate 
that the immediate region in which they are found is primi- 
tive, for this is disproved by the whole tenor of his observa- 
tions. If he means nothing more than that the pieces in 
question have such indicia as prove their origin from primi- 
tive rocks, this conclusion contains nothing improbable, 
for fragments of primitive rocks are not uncommon among 
volcanic ruins, and the mechanical analysis of lava by Cor- 
dier, is said to discover principally primitive minerals. | We 
