954 
MANGANESE DEPOSITS OP INDIA : DESCRIPTIVE. [PaRT IV : 
CLASS II. 
Deposits ehapacterized by the association of Piedmontite with the Ore, 
which occurs in Crystalline Limestone. 
GROUP VI. 
26. Mohugaon. 
27. Pali 
28. Ghogara (Peneh River). 
29. Mandvi Bir. 
30 Junawani. 
31. Junapani. 
32. Rajkota. 
These seven occurrences are not grouped together as being geo- 
graphically close to one another ; but because of their dissimilarity from 
all the other deposits in the Nagpur district, and similarity to one another 
as regards both mode of occurrence and mineralogy. Since the associated 
rocks are identical in each case, it seems possible that they all represent 
one horizon in the metamorphic series, this horizon having been broken 
up into widely separated outcrops by the system of faulting that almost 
certainly exists transverse to the general strike of the rocks of this district. 
It also seems possible, however, that the Pench River exposure re- 
presents one band, and the other six occurrences a separate band of the 
same rocks. 
The manganese-ore usually occurs as nodules of varying size, often 
elongated and twisted, and located in bands, in a piedmontite-bearing 
crystal-line limestone. Occasionally the ore is in the form of lenticular 
masses or even of small beds. In one case — the Pench River exposiu-e — 
there are nodules of piedmontite associated with the ore. It hence seems 
possible that some of the ore may have been formed by the alteration of the 
piedmontite ; but I think the main bulk of the ores is original and has 
been formed by the compression of original manganese oxides, deposited 
at the same time as the sediments from which the limestones have since 
been formed by metamorphism — sometimes direct, and sometimes with 
passage through a gneissic stage with subsequent chemical alteration. 
See pages 300 to 303. 
The ores themselves are usually mixtures of braunite with one of the 
manganates, usually the crystalline form hoilaudite, but sometimes the 
amorphous form psilomelane. 
Associated with the piedmontite-bearing limestones there is often a 
black or dark brown limestone, seen under the microscope to owe its colour 
