Chap. XV.] 
GONDITE SERIES ; ORIGIN. 
313 
phic and crystalline complex ; in fact such has been the fate of this very 
occurrence at the hands of previous workers in this area. Yet the grit un- 
derlying the manganese-ore deposit at Balaghat must undoubtedly 
be regarded as a part of the Chilpi series. On the west side of the Wain- 
ganga the whole of the metamorphic and crystalline complex has been 
mapped as a single formation both by me and by Mr. Datta, except 
for the big range of quartzites running in a general south-westerly direc- 
tion through Chandpur and Ambagarh in the Bhandara district. But 
if time could be foimd for a detailed survey of this area, on maps of a large 
scale where such are available, it would be possible to distinguish a large 
number of outcrops as the highly metamorphosed equivalents of the 
Chilpis. The quartzites and mica-schists can probably be regarded 
as such and could easily be distinguished ; but when it came to deciding 
which gneisses are to be regarded as metamorphosed stdimentaries 
or para-gneisses, and which are metamorphosed igneous rocks or ortho- 
gneisses, the work would have to be controlled and checked by a con- 
siderable amount of chemical analysis. That portions of this complex 
can fairly be regarded as the metamorphosed equivalents of the Chilpis 
is indicated by a very interesting microscopical feature of the mica. 
, . ^ , schists. On the low groimd to the east of Sita- 
Mica-scmsts and , . . . 
phyllites of Bhandara saongi Hill I collected a specimen of a very coarse- 
and Balaghat. grained silvery mica-schist. Under the microscope 
the rock is seen to contain — besides musco^'ite, quartz, and a certain 
quantity of felspar — a number of tiny perfectly idiomorphic lavender- 
coloured tourmalines, a considerable quantity of ottrelite noticeable 
as green specks in the hand-specimen, and lastly an abundance of small 
idiomorphic crystals of composite character. They are partly opaque 
black, suggesting an iron-ore such as magnetite or ilmenite, and partly 
transparent yellow, corresponding in all respects to rutile.^ Sometimes 
the boundaries between the iron-ore — which from its association with 
rutile is in all probability ilmenite— and the rutile are quite irregular ; 
but more frequently the two minerals are arranged in bands, correspond- 
ing in all probability to twinning planes of the rutile ; and the slide 
suggests that these composite grains were origmally entirely rutile and 
* The presence of considerable amounts of titanium in the Sitasacngi. Balaghat, 
and Utua, schists and phyllites has been proved by !tlr. T. R. Blyth. 
V. y 
