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6 Foreign Notices in Mineralogy, §¢. 
and that they are in part, if not wholly, of volcanic origin.* 
One of the specimens, which is now in my cabinet, is very 
much in favour of this opinion. It is a fragment of a Trap 
rock, composed of augite and felspar, and cannot readily be 
distinguished from portions of the Trap rocks of Iceland. 
This specimen is about six inches in length, and ‘has an ir- 
regular prismatic form. Nearly the whole of one side of it 
is covered with calcedony, and small rock crystals. This 
is evidently part of alarge drusy cavity. The calcedony has 
a slightly bluish colour, and is rather more than half an inch 
in thickness ; and the transparent crystals rest upon it. 
A second specimen is composed of jasper and calcedony. 
The jasper is red, (about the colour of arterial blood,) with 
bands of light yellow, and brown ; the surface is irregular, 
and is covered on one side with calcedony of a most deli- 
cate flesh colour, in small mamillary concretions, studded 
with innumerable minute brilliant crystalline points. 
The most singular specimen is a portion of a stalactite, 
which has been broken transversely. Its length is three 
inches and a half, its diameter rather more than two. The 
exterior layer, which is about a quarter of an inch thick, is 
composed of crystallized transparent quartz, within which is 
a layer of milk white calcedony of about the same thickness, 
and the centre of the specimen is filled by calcareous spar 
of a yellowish brown colour, and opaque. The calcareous 
spar is so hard near its junction with the calcedony, that it 
yields with difficulty to the kuife. It however effervesces 
with an acid. The central portion is considerably softer. 
Among these specimens are many globular, and ovoidal 
masses of calcedony, of various shades of white, grey, blue, 
aud red. ‘Their size varies from that of a hen’s egg to the 
diameter of eight or ten inches. They are hollow, and are 
lined with crystals of transparent quartz and calcareous 
spar ; of the latter I observed four forms, viz: primitive, 
inverse, cuborde, and metustatique of Hauy. The exterior 
of these geedes is irregular, having that indented surface so 
* Mr. J. Miens, in the Edin, Philo. Jour. No.6, has given a very interesting 
account of the discovery of New South Shetland, and from the information 
obtained by him from the mate of one of the vessels which had been there, 
is disposed to consider the coast as composed of chlorite slate, or ‘ schistose 
harnblend.’” 
