CHAPTER XX. 
GEOLOGY— concluded. 
Manganese in the Tertiary and Recent Formations. 
L:\teritic gravel or mangauese-ore pisolites — Manganese in the Tertiary — In tho 
post- tertiary — In recent deposits — In ponds and rivers — In deep-sea deposits— In 
manganiferous sands o.nd soils — In fault-rock of various ages. 
Lateritic Gravel (Mangauese-ore Pisolites). 
In many areas where manganese-ore deposits occur one finds, scat- 
tered over the surface of the ground, numerous 
Manganese -ore pisolites. ° . 
small rounded bodies of very uniform size, 
namely about that of a lentil or small pea. They are brownish-black in 
colour and, when fractured, are seen to be black inside and to consist of 
manganese-ore. These bodies can therefore be designated manganese-ore 
pisolites. A good example of their occurrence in considerable abundance 
is to be found at Kurmura in the Bhandara district. Here, on the low 
ground on the south side of the ore-ridge, they lie scattered in great 
abundance. When fractured they are found to be of two lands. 
Some of them are undoubtedly of detrital origin, 
Detrital pisolites. . . chip , , i 
consisting of rolled fragments of the manganese- 
ores occm'ring on tlie ore-ridge above. Such pisolites are, of course, 
very variable in character, on account of the variety of manganese- ores from 
which they have been formed ; many of them are seen to be com- 
posed of the hard grey braunite-psilomelane mixture. The pisolites of 
the other sort show a concentric structure when 
Concretionary ijisolites. , , , i r, ji .1 i-^ 
broken and are much softer than the generality 
of the pisolites of detrital origin. Their streak is usually not pure black, 
as it would be if the material of which they are composed were almost 
entirely manganese oxide ; but a brownish black, probably denoting 
the presence of a considerable proportion of oxide of iron intimately 
associated with the manganese oxide. In another mode of occurrence 
these pisohtes are scattered through clay, cither 
Modes of occurrence. .1 • 1 , ,1 • 1 » 1 r ,i • i-^ 
thickly or thinly. As before these pisolites 
are found, when broken open, to be some detrital and some concretion. 
ary in origin. The clay in which they occur is usually cither resting on 
or not far from a manganese- ore deposit. In the (,'entral Provinces, the 
