!)G1 
MANGANESE DEPOSITS OF INDIA : DESCRIPTIVE. [ParT IV : 
Olio nodule was separated into several pieces by parallel cracks 
to -jfo inch wide, filled with a light crimson mica, which showed the 
following pleochroism under the microscope : — 
il= lilac : 
b= yellowish pink ; 
C= light rose to lilac-rose. 
It is a fortunate thing, considering the unique interest and beauty 
Nature and (|iuility ^'^^^ exposure, that thesc manganese-ore nodules 
of the ores. can never be economically extracted. A sample 
was, however, taken by chipping from the outcrop of the nodules. The 
ore thus obtained was all extremely fine-grained, dark steel-grey, and 
usually showed concentric banding due to the structure of the nodules. 
Some of it could be scratched with little difficulty and some could not 
be scratched at all with a knife. Some looked quite pure and some 
contained little streaks of calcite, while a little limestone and piedmontite 
was attached to some pieces. Some pieces, rejected from the sample, 
consisted of alternate layers of ore and limestone. The result of a partial 
analysis at the Imperial Institute is as follows : — 
Sample No. 18. 
Manganese peroxide .... 
. 50-06 
Manganese protoxide .... 
. 13 fi? 
Ferric oxide ..... 
. e-8!) 
Silica (combined) .... 
. f)-78 
Phosphoric oxide .... 
. 0-09 
Moisture at 100°C 
. 0-21 
Carbon dioxide ..... 
. 3-49 
is equivalent to — 
Manganese ..... 
. 42-28 
. 4-82 
. 10-02 
Phosphorus ..... 
. 0-04 
Moisture ...... 
. 0-21 
analysis and physical characters 
of the ore indicate a mixture 
of braunite and a manganate, in some cases psilomelane and in others 
hoUandite. 
The limestone in which the nodules occur is usually the variety con- 
taining piedmontite. The latter, besides being abundantly dissemi- 
nated through the limestone in minute grains, is also often found as 
deep crimson-coloured nodules up to .3 and i inches long arranged in 
bands in the limestone. These nodules are some- 
times coarsely crystalline, but are more usually 
either finely crystalline or else fibrous in structure, the water-smoothed 
surfaces of the nodules then resembling crimson silk. In many cases 
she noduled consist of piedmontite on the periphery tin I manganese- 
Piedmontitc. 
