Chap. IV. ] 
PSILOMELANE. 
109 
It is usually found to be convenient to assume that the Fe203 present 
in the ore replaces an equivalent amount of Mn203 in the braunite, 
although it may also often be regarded as forming ferric manganate, 
Fe4(MnOg)3, and has been so regarded in some of the analyses scattered 
through the text. Now 6"00 Fe203 is equivalent to 5"92 Mn203, so 
that for the braunite above only 32 "95 — 5"92 of Mn203 is required; 
the composition of the braunite is therefore as follows : — 
Mn203 
Fe203 
MnO 
Si02 
27 -03 
6-00 
4-94 
4 20 
42-17 
Now 
and 
27 '03 Mn203 = 18 '82 manganese + 8 '21 oxygen. 
4-94 MnO = 3-82 „ +1 "12 
totalling 22-64 
Available in analysis . . 51 '40 
• •. remaining for psilomelane . 28 '76 
For the formation of psilomelane : — 
1 '19 AI2O3 require 
0-79 BaO 
0-84 CaO 
0 94 MgO „ 1 -20 
2 -27 K2O „ 1 "24 
0-23 NaaO „ 0-19 
0*02 CuO „ 0 01 
0 05 ZnO „ 0 03 
2 00 H2O „ 5-71 
+ 9-33 
+ 26-03 
+ 16-70 
1 -80 MnOs, giving 2 -99 Al4(Mn05)3 
0 27 „ 1 -06 Ba2Mn05 
0 -77 „ ,, 1 -61 Ca2Mn05 
„ 2-14 Mg2Mn05 
„ 3-51 K4Mn05 
„ 0-42 Na4Mn05 
„ O'OS Cu2Mn05 
„ 0-08 Zn2Mn05 
„ 7-71 H4Mn05 
11-22 MnOs 
Available . 
Left 
To forin]VIn2Mn05, ■ 
11 -04 oxygen, yielding 
1 1 -22 MnOs 
= 5 -99 Mn + 5 -23 0 
= 28 -76 IVIn + 16 -70 0 
22 -77 Mn + 11 -47 0 
22 -77 Mn require 
giving total of psilomelane as . 
apd leaving a surplus of 0 43 oxygen unused. 
19 -55 manganates 
33 -81 Mn2 MnOs 
53-36 
