Ixxx 
MANGANESE DEPOSITS OP INDIA. 
In places where the degree of metamorphism to which these rocks were 
subsequently subjected was not great, any layers of manganese oxides 
were consolidated into manganese-ores, mechanically mixed with any 
impurities that may have been mechanically deposited with the 
manganese oxides. A good example of this is the Balaghat manganese- 
ore deposit. 
But in places where these sediments with their manganiferous layers 
were subjected to considerably more intense metamorphism, through 
being folded in to a greater depth, a chemical reaction often took 
place between the manganese oxides and the clay or sand mixed 
with them. The result of such interaction was the formation of 
manganiferous silicates, especially the manganese-garnet, spessartite, and 
to a less extent the manganese-pyroxene, rhodonite. The series of 
rocks thus formed has been designated the gondite series after the race 
of so-called aborigines in the Central Provinces, known as the Gonds. The 
rocs of this series are of course only one particular facies of the 
Dharwar series. They are found principally in the Balaghdt, Bhandara, 
Chhindwara, and Nagpur districts, in the Central Provinces ; at Kajli- 
dongri in Jhabua State, Central India ; and at Jothvad in Narukot 
State, Bombay. 
By the subsequent oxy-alteration of these manganese- sihcate-rocks 
manganese-ores have been formed. As they are supposed to have been 
formed in depth, they are referred to as deep secondary ores, to distinguish 
them from the outcrop secondanj ores, often formed by the replacement 
of Dharwar rocks at the surface. 
The rocks and ores of the gondite series are found associated with 
a ' country ' of phyllites, schists, quartzites, and gneisses. Manganese- 
ores are also found in crystalline limestones in association with the 
manganiferous epidote, piedmontite. Now the determination of the 
origin of these ores obviously depends upon determining that of the 
crystalline limestones. I have elsewhere put forward an opinion that 
some of the crystalline limestones of the Chhindwara district have been 
formed by the chemical alteration of quartz-pyroxenes-gneisses under 
the influence of waters containing carbon dioxide. Briefly the idea is 
as follows : — 
Amongst the sediments deposited in Dharwar times, there must 
