CiiAP. jCXXVI.] 
nagpur: kandei. 
877 
The chief workings in the talus-ore are on the western and southern 
slopes of South Hill. Over this area the thicknessjof the detrital.ore 
deposit varies from a maximum of 12 feet to almost nothing, while on 
the north-east side of the ore-band in South Hill the detrital-ore beds 
vary from 6 to 16 feet in thickness immediately against the ore-body 
and rapidly tail out in the course of 20 to 30 yards. 
The excavations made near F at the east foot of North Hill show a 
thickness of 1 to 6 feet of detrital ore. These detrital deposits consist 
usually of pieces of ore of varying size, and fragments of the ' country,' 
with a more or less abundant interstitial red clay containing small pebbles 
of ore ; where the underlying rock is exposed there is usually seen in- 
tervening between the bed-rock and the detrital ore a layer, often about a 
foot thick, composed of little pisolitic concretions of manganese-ore set 
in red gritty clay. As will be seen from Plate 31 the size of the boulders 
and fragments of ore varies greatly ; in one place I estimated a single 
block of ore to weigh some 7 tons. In the south-east quarries on the 
south side of south-east end of South Hill there is an almost gradual 
passage, on passing away from the ore-band, from huge blocks of mangan- 
ese-ore practically in situ, to the ordinary detrital accumulations. This 
detrital ore is, of course, quarried, partly because it is necessary in order 
to work the ore in situ properly, and partly because it is, as a rule, profit- 
able to do so. As the ore fragments, except close to the ore-band, are 
usually covered with a ferruginous coating, it is necessary to fracture every 
one before stacking it, in order to make sure that it is of good quality. 
But all pebbles under 1 to 1^ inches diameter are rejected irrespective of 
quaUty. With regard to the amount of merchantable ore obtained 
from such deposits, I understand that the extreme upper limit is perhaps 
60% of the volume of the deposit ; but such a high percentage can only be 
obtained right against the ore-body. The lower limit is about 4% of 
the volume of the deposit, and the proportion obtained in different parts 
of the deposit varies between these limits. Such poor deposits as those 
yielding only 4% of merchantable ore would not be worked except for 
the facts that (1) it is necessary to work the deposits uniformly, and (2) 
it is never known when the barren deposits may change to better. 
The excavations on the south-west side of the hill have in many places 
been carried down to the underlying rock, usually mica-schist. They 
show moreover that in several places there are layers of quartz and 
quartzite fragments in these deposits. One section seen was : — 
7 feet. Ore rubble. 
6 inches to 1 foot. White saccharoidal quarfczifce fragments. 
1 foot. Ore and quartzite gravel. 
3 inches. Grey quartzite fragments. , 
1 foot. Mioa-schist »» 
