34 
Records of the Geological Survey of India. 
[vol. vix. 
Small veins of segvegitic pegmatite, having the same composition as the surrounding 
rock, from which they only differ in largeness of crystallization, are not uncommon in the 
gneiss; they seldom exceed two or three feet in thickness, are sometimes short and lenticular, 
in other cases traceable for some little distance. It is sometimes not easy to distinguish 
these from the granite veins to be described further on. 
Limestone .—Calcareous rocks are very rare in the metamorphics of this region. In 
fact I have observed none in sheets 7 or 8 except a thick band of dolomitic limestone at 
Dbelwa (north of Gawan), which may, however, belong to the submetamorphic series, 
and a few thin layers of the same rock close to Gawan. 
In the bed of the Patru nadi, north-east of Gulgo, (east side of sheet 3) the following 
section is exposed:— 
a. —Hornblende schist overlaid by 
b. —Largely crystalline white limestone containing scales of light green mica here 
and there; this bed is about 6 feet thick, and is covered by 
c .—A peculiar mixture of garnet and coccolite containing traces of galena and copper. 
In places the two minerals are well intermixed, in others the garnet occurs in a 
pure massive form (so called ealderite); only a few feet of this rock (r) is seen. 
The beds in this section, which is on the south side of the stream, dip at about 15° 
to east-north-east, and the same strata are seen on the opposite side also, the distance from 
bank to bank, or length of visible outcrop, being perhaps 60 yards. An analysis of the 
limestone by Mr. Tween yielded— 
Carbonate of lime ... 
„ magnesia 
Oxide of iron and alumina 
Insoluble ... ... 
... 88-80 
... 307 
... -61 
... 7-1$ 
99-68 
The locality is worth notice, as being within fifteen miles of Mahishmon station on the 
Karharbari branch of the East Indian Railway, over a country traversable by carts; more 
especially so in the event of iron works being started at Raniganj, the distance of which 
from Mahishmon is seventy-nine miles by rail. The bed is thin no doubt, but it may extend a 
considerable distance, and perhaps increase in thickness along the strike, and there is further 
the possibility of its being brought to the surface elsewhere in the neighbourhood by rolls in 
the strata. These points can only be determined by a close survey of the ground, which is 
beyond the limits of the area at present completed. A limited supply of very good 
mineral, either for burning or as a flux, can, however, undoubtedly be obtained there, 
whilst there is the possibility that if the bed were opened out, it would prove of considerable 
value. The nearest known locality where limestone occurs plentifully is Rhotasgarh on the 
Son, the transport of stone from which to Raniganj would involve over eighty miles of river 
and 236 miles of railway can-iage; a bed, therefore, like the above, although it may perhaps 
not prove to be of much importance, is still well worth a trial. 
Lead-ores — Galena is sparsely disseminated here and there through the garnet and 
coccolite rock mentioned above, as overlying the limestone ; and minute specks of copper 
pyrites and blende are also visible, the rock in one or two places being stained bright green 
by copper. 
On the north bank of the river the beds are cut through by a nearly vertical granite 
vein, which also contains traces of galena, and the felspar in which is partly amazonstone, 
the color being probably due to copper. Both lead and copper, however, merely occur very 
sparingly disseminated through these rocks. There is no indication of a lode, or any 
