GU 
MA.\t;.\>KSK Dlii'OSl'iS OF INDIA : DESCIUI'TIVE. [PaRT IV : 
ores imist suflter gradual replacement, which in all but the case of Chikhli 
has become complete. The manganese forming these nodules has there- 
fore perhaps been derived : — 
1. Partly by concentration during decomposition and removal of 
the basaltic lavas. 
2. Partly from solutions bringing it from the laterite masses. 
The laterite cap must once have covered the ground where the man- 
ganese now occurs ; and it becomes a question as to whether these so- 
called ' soils ' ai'e really such, formed by decomposition of the traps at the 
surface posterior to the removal of the laterite cap ; or whether they 
existed beneath the laterite as a stratum intervening in places between 
the laterite and the traps, and serving a locus for the deposition of the 
manganese removed during the formation of the laterite. 
As already mentioned all the ores found were psilomelane of concre- 
:N'ii ure and quality tionary origin. I took samples of the ores from 
of the ores. the four localities visited. These were analysed 
by Messrs. J. and H. S. Pattinson of Newcastle, and the results are in- 
serted under the respective localities. The limits and mean of these 
analyses are as follows : — 
Limits. 
Mean. 
Manganese .... 
Iron ..... 
Silica ..... 
Phosphorus .... 
Moisture ..... 
37-58 to 45-62 
4--10 to 9-25 
2-90 to 4-75 
0- 036 to 0-098 
1- 70 to 2-^0 
40-79 
6-94 
3-75 
0- 067 
1- 99 
From this it will be seen that the ores are low grade manganese-ores ; but 
they are, except for their low manganese, of good quality, being low in 
both silica and phosphorus. 
The combined silica shown in the analyses does not indicate the pre- 
sence of braunite ; it is probably due to the presence of residual portions 
of siliceous material from the traps, such as was noticed in the ore oi 
ChikhU. The large amounts of combined water are also noticeable. 
Judging from the foregoing figures, there is no doubt that manganese- 
ores of fair quality are to be found at several points 
Ecouoiuic vn!uc. ^^^^ Mahabaleshwar plateau, and doubtless also 
in iniiiiy other parts of the Western Ghats where similar conditions pre- 
