250 
MICA-SLATE, CLAY-SLATE, AND PRIMITIVE LIMESTONE. 
chapter ; and the description of the iron ores 
may be consulted in the account of the 
mines. 
The chlorit-slate and porphyritic green- 
stone appear to be peculiar to this for- 
mation. 
(B) CHLORIT-SLATE. 
Its colours are emerald and grass green. 
It occurs massive. Internal lustre, pearly. 
Fracture, scaly foliated. Distinct con- 
cretions, thin lamellar. Lustre of the dis- 
tinct concretions, shining. It is opaque, 
and it alfords a light-coloured streak. 
It is soft, and perfectly sectile. It is 
meagre to the feel. Specific gravity, 3. 
It occurs in large quantity in the lower 
strata of hornblende-slate, and is found at 
Chimtouly, in the vicinity of the iron mines. 
It also occurs at the southern foot of Choura 
Pany, near Belket, where its scaly laminee 
alternate with thin laminae of quartz. It is 
the substance that gives the slaty structure 
to hornblende-slate. 
(C) PORPHYRITIC GREEN-STONE. 
This rock is found at the southern foot of 
the principal mountain chain, where it forms 
at Belket, a portion of the bed of the river 
Ludhoo. I have not been able fully to ascer- 
tain its extent and geognostic relations ; and 
as this is a point of first-rate importance, 
it would be improper to hazard an opinion 
upon it. 
It will be seen on inspection of the map, 
as well as from what is said in the descrip- 
tion of Belket, that if the porphyritic green- 
stone passes under the elevated mass of 
strata composing the southern declivity of 
Choura Pany, that then those philosophers, 
who contend that the strata of mountains 
have been elevated to their present position, 
by the expansive operation of heat, confined 
in the centre of the earth, would find in the 
peculiar position of this green-stone, a strong 
argument in favour of their doctrine ; but if, 
on the other hand, it should appear on further 
inquiry, that this formation, like the others 
we have described, presents the character of 
a deposite from above ; then, of course, the 
first argument would come to nothing. 
This rock is composed apparently of equal 
parts of hornblende and felspar, in minute 
crystals, mechanically mixed, so as at first 
sight to look somewhat like a fine granite. 
It is not stratified, but divided in all direc- 
tions by adventitious rifts, which give it a 
brecciated structure in large masses. The 
fragmented pieces are usually trapezoidal. 
It is hard, and not particularly heavy.” 
We now come to the primitive forma- 
tions — mica-slate, clay-slate, and primitive 
limestone. Mica-slate is found at Durgura, 
alternating with gypsum, and a micaceous 
kind of clay-slate, which, from its geognostic 
situation, may be considered to be interme- 
diate between mica-slate and clay-slate. This 
also occurs associated with similar rocks at 
Choura Pany ; it rests^on hornblende -slate, 
and is composed of small grains of quartz, 
some felspar, and a considerable proportion 
of grey or silvery mica. Mean direction of 
the strata W. N. W. ; mean dip, 500. 
Gypsum is found in beds from 50 to 300 
feet thick strata, subdivided by numerous 
slaty rifts running parallel to the strata 
which seem to divide the rocks into tables 
from two to six inches. The colour of these 
strata is reddish white, and greenish white ; 
lustre glimmering, and sometimes glistening 
jn the principal fractures ; while that of the 
cross fractures is pearly ; large fractures 
slaty and tabular ; small pieces wedge-shap- 
ed : it is faintly translucent on the edges ; 
semi-hard and frangible* 
“ Specific gravity of the reddish coloured 
variety, from Durgura, 2*612, and of the 
greenish white kind, from the same place, 
2*574 and 2‘669 ; while a variety of the same 
from beds in hornblende-slate at Chimtouly, 
is, 2*3. 
Chemical characters. It is infusible be- 
fore the greatest heat of the blow-pipe, either 
when placed on charcoal or held in the forceps. 
Even with the addition of borax, and the 
flame directed to the edges of the laminae, it 
evinced little signs of fusibility ; nor is it 
soluble in any proportion of water. 
These experiments were not made on the 
specimen from Chimtouly, which appears 
to be a purer gypsum than the others, from 
its more compact and sparry character, as 
well as from its containing less mica.” 
The extracts we have given shews fully 
our author’s mode of description. He then 
proceeds to describe the great formation of 
clay-slate, which composes at least the sixth 
part of the whole province, and is stretched 
in conformable strata over the mica- slate 
and trap rocks. It commences on the N. E. 
acclivity of the principal mountain chain 
under the out-going of the substratum, at 
the elevation of 7000 feet. Primitive lime- 
stone composes the northern acclivity of j 
Takill ; and from thence it extends in a 
north-westerly direction for many miles. j 
“In a small river valley, which partly 
separates Takill from the Oudepore group, 
this rock forms the most frightful precipices 
on both sides that can well be imagined. | 
These precipices compose broken, and i 
seemingly tottering mountain acclivities, 
that ascend in places for three or four thou- , 
sand feet, at various angles betw^'cn 45^ and ! 
