76 MANGANiiSE DEPOSITS OF INDIA : MINERALOGY. [ PaRT I : 
leaving a remainder of 48 per cent., which, as the amounts of free sUica, 
phosphoric oxide and moistm"e are not large, can be taken as roughly 
corresponding to the percentage of psilomelane in the ore. That is the 
composition of the sample can be taken as roughly 52 per cent, of 
braunite, and 48 per cent, of psilomelane. The method of calculating out 
a complete analysis into terms of its mineral composition is explained 
on page 108 ; many examples of such re- arranged analyses will be found 
scattered through the pages given up to the description of the deposits 
of the Nagpur district. 
Occasionally the percentage of braunite calculated in this way seems 
to be considerably less than the aspect of the specimen would lead one to 
expect. An example is the analysis of a specimen of coarsely crystaUized 
ore from Lohdongri given on page 917. This ore would seem to contain 
at least 80 per cent, of braimite. Calculation in the ordinary way only 
shows a percentage of 68 "5 per cent, of braunite. This probably means 
that the braunite in this ore has one of the other formulae, probably 
7Mn203.2MnSi03 containing only 8"8 per cent, of siUca, instead of 10 per 
cent, as in the braunites of the formula 3Mn203.MnSi03. This would 
give a percentage of 77"4 of braunite ; whilst the formula 4Mn203. 
MnSi03, corresponding to 7"9 per cent, of sihca, would give 86'3 per cent, 
braimite in the ore, and one of these two latter figures would seem to 
correspond more exactly with the aspect of the ore than the first. 
Appendix. — Since the foregoing was sent to the press, Mr. Blyth has 
been able to analyse the braunite of Sitapar in the 
br^^TnUr' °^ Chhindwara district, Central Provinces. The mineral 
taken for analysis was obtained from the complex 
ores of this locality, consisting of sitaparite, hoUandite, braunite, 
pyiolusite, and an arsenate. The braunite occurs in small black 
lustrous grains. The amount obtained fit for analysis was 1" 14 grammes. 
The specific gravity was found to be 4" 798. The result of the analysis is 
shown below : — 
Specimen No. 843 Ci. 
Manganese peroxide . . . . . . . . . . 37 ' 10 
Manganese protoxide . . . . . . . . . . 41'10 
Ferric oxide 7 '92 
Alumina 0"92 
Baryta trace 
Lime 4-28 
Magnesia ............ 0 '94 
Silica 8-62 
Moisture at 100°C O'lO 
100 -88 
Manganese ............ 55 '28 
lion 5 '64 
