Chap. XX.] 
Manganese-ore pisolites. 
393 
forming the ' country ' of a deposit, along narrow zones traversed by 
circulating surface waters. In all probability pisolites of concretionary 
origin are also formed directly in the interstices of the talus-ore accu- 
mulations and in any porous soUs. Thus the mixed accumulations 
of pisolites must have often been formed by the denudation of the rock, 
such as mica-schist, in which the concretionary pisolites were formed, 
with the separation of these pisolites from their matrix, and their subse- 
quent admixture with pisolites of detrital origin, only those detrital 
pisoUtes of approximately the same size as the average size of the con- 
cretionary pisolites being deposited by water along with the latter. 
Hence, of the different occurrences of pisolites mentioned above, 
the ones in clay are in all probability often 
iSuniniary of origin. ^. , ri-x- --i^i j_- 
entirely of derivative origin, both concretionary 
and detrital pisolites having been washed into the clay. In the pisolitic 
deposits underlying the talus- ore accumulations the concretionary 
pisoUtes may have been in part rolled into the deposits along with the 
detrital pisolites, at the time of the formation of these deposits, and may 
have been in part subsequently deposited by manganiferous solutions 
percolating through these porous deposits. The pisolites, such as those 
of Kurmura, that are found lying loosely scattered on the surface of the 
ground, have probably all, even when concretionary in origin, been 
mechanically carried to their present position ; for it does not seem 
probable that such concretions would form actually on the surface of 
the gromid. Were such an accumulation as that of Kurmura to be 
now covered up by talus-ores derived from the hUl above, we should 
get an exact parallel to the talus- ore deposits at present being worked ; 
for the talus accumulations would be separated from the underlying 
rock by a layer of manganese- ore pisolites, of which a certain number 
would doubtless get mixed up with the fragments of ore in the talus-ore 
deposits. 
Although all the examples quoted above are in the Central Pro- 
vinces, yet such pisolitic deposits are equally common in association 
with the manganese-ore deposits of Vizagapatam and other parts of 
India, and will probably be found to be of common occurrence 
wherever manganese-ore deposits are found. 
As an example of abundant pisolites scattered through sandy soil 
mention may be made of the occurrence at Gudhiari in the Ganjam 
district (page 1036). 
