71 n MANGANESE DEPOSITS OF INDIA : DESCEIPTIVE. [ParT IV : 
ore interbanded with red, black, and sometimes grey, quartzites. and is 
usually separated from the underljang schistose grit by a thickness 
of fine-grained whitish, yellowish, or pinkish, jaspery quartzites. These 
are sometimes rendered schistose by layers of tiny scales of sericite and at 
other times have a sugary appearance due to these scales being uni- 
formly disseminated through the quartz-mosaic seen under the mi- 
croscope. These quartzites are often as soft and friable as sandstones, 
and are frequently replaced in part by oxides of manganese and iron, 
the result of a further continuance of this process being black and brown 
replacement-rocks respectively. In some cases the replacement takes 
place along veins, which may increase in number and width until the 
whole rock is replaced; while at other times the oxide of iron or man- 
ganese, as the case may be, finds its way along the boundary between 
each grain and replaces them from the periphery inwards so that the usual 
result is a network of opaque oxides enclosing residual quartz grains. 
The rej)lacement by manganese often takes place in patches, the resul- 
tant rock being very similar in appearance to that figured on PI. 10, fig. 1 . 
The hard red jaspery quartzite is seen under the microscope to con- 
The red and black sist of a fine-grained mosaic of quartz, each grain 
quartzites. of which contains a cloud of minute particles of 
red dust, doubtless ferric oxide, the cloud usually occurring towards 
the centre of the grain so as to leave the periphery clear. This quartz- 
ite is thus identical in all respects with the red quartzites found at 
Kajlidongri, Jhabua State. The bands of it are not usually con- 
tinuous for any distance, but thin out in lenticular fashion, and 
evidently have often been effaced by complete replacement with 
manganese-oxides so as to produce good manganese-ore. The accom- 
panying figure shows an actual case seen in one place. The two nodules, 
A and B, were doubtless once part of a continuous layer of quartzite 
that has since been largely replaced by manganese -ore. An interest- 
ing feature is that the ends of these nodules are rounded and not 
drawn out to a point. In many places in the ore-body the red quartzite 
