386 
MANGANESE DEPOSITS OF INDIA : GEOLOGY. [PaRT II 1 
The only lateritoid deposits that it may pay to work at times of low 
prices are those oi Sandur, and some of those of Mysore (particularly 
Kumsi). The names given in italics show the areas from which ore 
has been exported. 
The inclusion of the Sandur deposits amongst the lateritoid ones 
The Sandur deposits ^^^^ some surprise, consider- 
ing their enormous size as compared with the 
majority of the late itoid deposits. It is my opinion, however, that 
the Sandur deposits — certainly those of the Eamandrug area, and pro- 
bably those of the Kamataru area — have been formed by the same 
process of superficial replacement of rocks containing but little 
manganese. I do not propose to go further into the mode of origin of 
those and other lateritoid deposits in this portion of the Memoir; 
but for further details I would refer the reader particularly to the 
accounts of the Sandur deposits given in Part IV of this Memoir, and 
also to the accounts of the Mysore and Jabalpur deposits. 
Some of those who may object to the deposits I have ternied 
lateritoid being regarded as a variety of 
Limitation of the term , ^ ■, ,i ^ • i i 
' lateritoid'. laterite may say that, it superficial replace- 
ment deposits of iron and manganese are to be 
called lateritoid, it will be necessary to extend the term to ores of 
other metals that have been formed by similar processes, such as 
may occur in fissure veins, near the surface. This may be avoided 
by restricting the term to replacement deposits of the oxides of iron, 
manganese, aluminium, and titanium, the four constituents character- 
istic of the true high-level laterite. 
Although, as mentioned above, many masses of laterite are apparent- 
ly quite free from manganese ; and although the manganese when present 
has probably been concentrated by segregative processes, so that the 
manganese from a considerable area of ground has been formed into 
Distribution of manc ani- concretions distributed over a much smaller 
ferous hiterites, and la tei itoid. area of laterite : yet one would expect the man- 
ganiferous laterites (and lateritoid) to bear in general mode of occurrerce 
some relation to the nature of the underlying rocks, and hence to be 
found in those areas where the older rocks are the most highly 
manganiferous. Such is found to be the case. Laterite found 
on the Deccan Trap, the rocks of which contain only a com- 
paratively small amount of manganese, is, as far as is known, fairly free 
from any manganese- ores, the Bidar occurrence being the most notable 
exception ; whilst laterite and lateritoid found on the outcrops of rocks 
