956 MANGANESE DEPOSITS OF INDIA : DESCEIPTIVE. [PaeT IV : 
Separated from the crvstalline limestones by a shallow depression, 
.Mohugaon 
HILLS NOT 
EXAMINED 
] Alluvium 
Ciystalline limestone 
1 Matigtwiferaus Limettcne 
\CalcJpl{/r» 
Fig. 73. — Sketch-plan of the Mohugaoii manganese-ore deposit. 
there occiirs to the south an outcrop of what may be described as 
calciphyre with very little calcite ; and as these calciphyres strike so 
as to run into the h'mestones, the two rocks must be separated by a 
fault, as shown in the section (fig. 73). 
The late Mr. Gow Smith made a few shallow pits on and to the south of 
the above outcrop of crystalline limestones, and these showed a foot or 
two of manganese nodules and limestones debris mixed, resting on the 
fresh rock ; therefore there is little hope of any marketable ore being ob- 
tained here. 
The ore itself is dark grey, crystalline, and is probably a mixture of 
braunite and hollandite. The specific gravity varies from 4-00 to 4-80. 
That the black crystalline limestone is of no commercial value is 
shown by the following analysis by myself : l — 
]VIn02 20-99 
MnO 5-83 
re203 1-99 
BaO 0-04 
CaO 35-89 
Insoluble .siliceous residue ....... 3-47 
P2O5 0 12 
Water (combined) ........ 2-86 
Moi,sture at 100°C 1-27 
CO2 27-46 
99-92 
1 In the form in which this analysis was first reported [JBec. G. S. I. XXXI, p. 47, 
(1903)] the presence of 17-27 per cent. SrO was shown ; owing to the lack of requisite 
chemicals in the Geological Survey laboratory I had to divide the alkaline earths 
into CaO and SrO (which was supposed from qualitative tests to be present) by weigh- 
ing first as carbonates and then, after ('alcination, as oxides. This method is of course 
unsatisfactory, and later, feeling doubtful of the presence of so much strontium, I ex- 
amined the rock spectroscopically and could not detect the presence of this constituent. 
