344 
MANGANESE DEPOSITS OF INDIA : GEOLOGY. 
[Part 11 : 
Manegaon, Ramdongri. and Waregaon, all in the Nagpur district. 
Sometimes the manganese-ore in these quartzites occurs in small 
patches rather than in separate needles, as in fig. 2 of Plate 13. 
This section also shows what looks hke a cavity lined with delicate black 
needles of a manganese mineral. Crossing the nicols shows, however, 
that this supposed cavity is really filled with mosaic quartz into which 
the needles project. 
Bright brick-red quartzites are also of fairly frequent occurrence, as, 
^ ^ ^ for example, at Balaghat, Ukua, and Kajlidongri, 
qii.u zi e. Like the black quartzites, these red varieties are 
very fine-grained, so that under the microscope they show a fine mosaic. 
The red colour is then seen to be due to the presence in the interior of 
each grain of a small cloud, usually collected towards the centre, of a red 
dust, which is in all probability ferric oxide or finely divided hematite. 
That it does occur inside the separate grains and not along their 
junctions is shown by the iact that if a piece of the rock be powdered and 
boiled with hydrochloric acid it does not lose its colour. If, however, 
the rock be finely powdered and fused with fusion mixture the iron 
can be extracted. 
At both Kandri and Mansar there is a rock, which occurs in close 
Mang,aiiferoiis association with the ore-body, that looks at first 
sight like a rather fine-grained quartzite. It is 
pinkish to whitish in colour. A closer examination, however, shows 
that it is finely crystalline and contains scattered grains and streaks 
of a black mineral that is magnetic, but not sufficiently so for 
magnetite ; and since this mineral gives a reaction for manganese it is 
either manganmagnetite or, less probably, braunite. It will require a 
separation of a considerable quantity of the mineral before this point 
can be settled ; for it only occurs in tiny grains in the rock. Under the 
microscope ^the rock is seen to consist of a rather fine-grained aggre- 
gate of quartz and microcline, and sometimes plagioclase, with fairly 
abundant scattered granules of the black ore mentioned above. It 
sometimes, but not often, except near the ore-body, contains a little 
yellow garnet, presumably spessartite, in streaks ; more often it 
glistens in the hand-specimen from the presence of fairly abundant 
scales of muscovite-mica, although this last constituent may be 
entirely absent. The rock may be called a manganiferous gneiss, 
or ev3n manganmagnetite-gneiss, and has probably resulted from the 
metamorphisni of sediments that were deposited immediately before 
