314 
MANGANESE DEPOSITS OP INDIA : GEOLOGY. 
[ Paet II : 
that they have since been partly converted into ilmenite. An alternative 
view is that the structure is original and due to an intergrowth of these 
two minerals during the metamorphism of the sediments from which this 
rock was presumably derived, their arrangement being determined by the 
strong tendency to twinning possessed by rutile. This rock was collected 
in a region where all the rocks are so highly metamorphosed that one 
would not at first suspect the presence of the Chilpis. The interest and 
importance of this rock lies in the fact that the phyllites occupying 
the ridge immediately to the west of the Balaghat ore-ridge are found, 
although usually much less coarsely crystalline, to show exactly the same 
minerals as the Sitasaongi rock : so that it would often be impossible to 
separate the slides prepared from the rocks of the two localities once 
they had become mixed. This extraordinary likeness extends even to 
the structure of the complex rutile-ilmenite grains. In this neighbour- 
hood there is, of course, no doubt that these phyllites belong to the Chilpi- 
Ghat series. Hence there can be little doubt that the Sitasaongi rock 
also belongs to the Chilpi series, although it is in a more meta- 
morphosed region than at Balaghat. But it must not be supposed that 
all the Chilpi phyllites and mica-schists are petrologically precisely 
the same as the rock described above. Thus, of some specimens of 
mica-schist collected from the Chilpi area near Ukua, one specimen 
shows the tourmaline and ottrelite, but not the composite rutile- 
ilmenite grains. Instead of the latter it contains scattered grains of a 
black iron-ore round each of which there is a beautiful halo of red 
hematite. Whilst another specimen from the same locality contains, in 
addition to the usual constituents, sphene and colourless garnet(?). 
Similar interesting comparisons could easily be made between other 
rocks of the Chilpis and metamorphic and crystalline series, respec- 
tively, but none of them are so striking as the example given above. 
When one comes to examine the ' country ' of the gondite series it at 
The ' couatty ' of once becomes evident that the rocks most closely 
the gondite series. associated with the manganese-bearing rocks and 
ores are mica-schists, quartzites, and more rarely schistose gneisses, 
which are usual y very siliceous. Rarely, in fact practically never, are 
the rocks of the gondite series closely associated with hornblende-schists, 
crystalline limestones (I am referring here, of course, to the manganese 
bearing rocks free from piedmontite), or gneisses of igneous origin. This 
