296 
MANGANESE DEPOSITS OP INDIA : GEOLOGY. 
[Part II : 
Mineral Veins and Intrusives. 
The waters that percolated through the masses of manganese-silicate- 
^ rock and manganese-ore towards the end of the fold- 
ininDraHzed°° waters i^ig of the Dharwars must, however, have contained 
during the metaiaor- many other substances in solution besides oxygen 
bodies. ° * ^ carbon dioxide. In fact, if one can judge from 
the unusual minerals often foimd in the manganese- 
ore deposits at the present day, these waters must have contained 
arsenic, barium, and possibly some of the rare elements, as 
e\adenced by the presence of arsenates at Kajlidongri in Jhabua 
and Sitapar in Chhindwara, by the almost invariable presence of small 
quantities of arsenic in the manganese- ores of the Central Provinces, 
and by the presence of barytes at Chargaon in the Nagpur district. More- 
over, probably during the folding, the Dharwars were at times frac- 
Veins traversing tured with the formation of fissures that acted 
the ore-bodies. as a passage for mineralized solutions. The best 
example of this phenomenon is at the Kajlidongri mine, where the ore- 
beds are traversed by a series of quartz veins containing barytes, a com- 
plex arsenate, and the manganate of barium, iron, and manganese, to 
which the name of hollandite has been given. The manganese-ores 
also frequently contain very small quantities of nickel and cobalt, and 
more rarely of copper, zinc, and lead. It is, of course, not possible to say 
whether these rarer constituents were present in the manganiferous 
sediments as originally deposited or whether they were subsequently 
introduced. It seems probable, however, that they were to a large 
extent introduced into the deposits during the time that they were being 
folded and subjected to high pressures and temperatures, this especially 
applying to the veins. The source of these introduced constituents was 
probably heated waters derived from masses of plutonic rock, whence 
they brought their metalliferous burden. 
In many of the deposits, as exposed in the mines, masses of peg- 
Rocks intrusive in matite or other acid igneous rock are found, con- 
the ore-bodies. ceming the intrusive relation of which with regard 
to the manganese-ore bodies there is often unequivocal evidence. 
These intrusives would no doubt have solidified in the majority of 
cases as ordinary granite or pegmatite veins, had they traversed ordinary 
gneisses, schists, or quartzites. But in piercing the manganese-ore bodies 
they took the opportunity to absorb portions of the rocks through which 
they passed, with the consequence that when they solidified the absorbed 
