l070 MANGAiSiESE DEPOSITS OF INDIA : DESCRIPTIVE. [ PaRT IV : 
On the assumption that the braunite has a composition corre- 
sponding to the formula 7Mn203. 2Mn8i03, the analysis A. 334 can 
be expressed in terms of the niineralogical composition as follows : — 
Specimen No. A. 334. 
Apatite .... 
Braunite (including 6-57 Fe^Oa) 
Psilomelane : — 
Al4(Mn05) 
Ba^MnOg 
CajMnOa 
Mg^MuOj 
KiMnOg 
NaiMnOj 
Co^MnOj 
NijMnOs 
CuaMnOa 
ZnzMnOs 
HiMnOo 
Mn,MnO= 
Sulphur 
TiO., . 
Moisture at IDO". C. 
Surplus oxygen 
3-47 
0-87 
0-04 
0-73 
5-8o 
0-38 
0-08 
0-0^ 
0-07 
0-16 
10-03 
53-20 
74-91 
1-132 
22-75 
74-91 
0-025 
0-06 
0- 30 
99-177 
1- 02 
100-197 
The oxygen error is rather large ; but may be due either to the 
presence of some Mn4(Mn05)3, or to other constituents in the speci- 
men, such as spots of soft black oxide. 
The foregoing ores seem to have been formed by the alteration 
in situ, with accession of further supplies of manganese oxide from other 
parts of the rock- mass, of masses of spandite-rock ; but frequently 
ores are formed in the midst either ol rocks containing no manganese, 
such as the quartz-felspar-rocks and their resultant lithomarges, or in 
rocks, such as apatite-spandits-felspar-rock, in which the percentage 
of original manganese is small. In such cases the resultant ore formed 
bv replacement of the pre-existing rock, whatever it may have been, 
is pyrolusite or compact psilomelane. A specimen of such pyrolusite 
