Chat-. XXXVI.] 
NAGPUR 1 MOIUJGAON. 
955 
to the deposition of oxides of manganese along the cleavage and twinning 
planes of the calcite, in the same way as I have described for the Chhiiid- 
wiira district. 1 
As shown by the analysis of the specimen given on page 956 the 
amount of manganese in these black limestones may rise to nearly 18 per 
cent. This same rock often contains spessartite also. The limestone 
sometimes contains bright shining specks of manganese-ore, probably 
representing original rhodonite. These are of considerable interest ; 
for when this rock undergoes silicification, i. e., is partly or almost en- 
tirely replaced by silica with the formation of chert, as so often happens 
amongst the limestones of this region, the manganese-ore is left as bright 
shining specks in the resulting chert, to the history of which it affords a 
ready clue. 
At Pali, in addition to the ores mentioned above, there is also found 
some very beautiful pyrolusite of secondary origin, noticed in detail 
on page 959. 
Considering the mode of occurrence of the manganese- ore, it can seldom 
be profitably worked, involving as it does the quarrying of a large amount 
of limestone to obtain a relatively small amount of manganese-ore. When, 
however, the manganese-ore occurs in lenticular masses or small 
beds then it may pay to work it ; moreover, by the weathering away^ 
of the limestones at the surface residual accumulations of nodules 
of ore of considerable size may be formed. These too would often 
pay to work. 
26. Mohugaon. 
The outcrop of manganiferous limestone is about 1 mile east- 
south-east of Mohugaon village and occurs in some low ridges of 
crystalline limestones striking E. 10° N. The actual ridge in which the 
manganese occurs is about one furlong in length and is composed of 
parallel bands of rock of varying composition dipping at about 40° to 
S. 10° E. 
These bands, reckoning from north to south have outcrop widths as 
follows : — 
(1) : — 12 feet ]>ink limestone with green accessories; 
(2) : — 30 feet grey limestone with manganese- ore nodules and [liedmontito ; 
(3) : - 9 feet brownish black limestone with spessnitite-bearing patches; 
(4) : — 36 feet same as (1) ; 
(5) : — 24 feet same as (3). 
1 Bee. G. S. I., XXXIII, p. 201, (1906). 
