392 
MANGANESE DEPOSITS OF INDIA : GEOLOGY. [ PaRT II 
various ways. If the manganese were held in solution by carbon 
dioxide as the bicarbonate, and the carbon dioxide should be released, 
either by the rapid motion of the solvent waters, or by their coming 
within range of evaporating agencies, as they would at the surface, the 
manganese would, in the absence of oxidizing influences, be deposited 
as carbonate, only to be oxidized later ; or, if subject to oxidation at 
the same time as the carbon dioxide was released, it would be deposited 
directly as oxide. Another way in which the manganese might be 
removed from solution is by the waters coming in contact with the 
atmosphere, or with air entangled between the particles of soil and 
rock a little below the surface. In this case, whether the carbon 
dioxide were released or not, the manganese salts would probably 
be oxidized with deposition of manganese in either the sesquioxide or 
peroxide form ; whUst, if the solvent for the manganese were organic 
acids, the deposition of the manganese might easily take place if the 
oxidizing influences were stronger than the dissolving tendencies of the 
organic acids, which, indeed, might themselves be broken up under 
the same conditions. The manganese carbonate or oxide liberated 
in one of these ways would by preference deposit itself against already 
deposited manganese carbonate or oxide, and the tendency would be 
for this deposition to take place in concentric layers, any carbonate 
deposited becoming in all probability oxidized almost as soon as depo- 
sited. The method of deposition is thus easy to understand. The 
only point requiring elucidation is where did this deposition take 
place ? The answer is supplied by two sections. One of these, seen 
Sections at ISIansiir and at Mansar, is figured on page 884, and shows 
Beldoiigri. that pisolites of manganese oxide have been 
formed in the mica-schist along the junction of this rock, both with 
the manganese- ore in aitu, and with the overlying talus deposits. 
From this it seems certain that these particular pisolites were deposited 
after the accumulation of these talus deposits and are probably still 
in process of formation ; especially as the mica-scliists, even in the dry 
weather, are wet, showing that probably the junction of the ore and schist 
acts as a directing influence for circulating waters. The other case 
was seen in the Beldongri quarry (see page 910), where mica-schist was 
again seen to contain numerous scattered pisolites of concretionary 
origin, the schist being overlain by pisolites set in a ferruginous 
clay, and this by a pisolitic gravel of which the separate pisolites were 
apparently mostly of detrital origin. Hence it is probable that a portion 
of the concretionary pisolites is formed in the mica-schist so often 
