228 
MANGANESE DEPOSITS OF INDIA : MINERALOGY. [ PaRT I : 
Table 20. 
A key to the identification of the black, 
I. Not scratched by a Penknife. 
Manganmagnetitc 
2. Vredenburgite 
3. Sitapaiite 
4. Braunite 
5. Frank! inite 
6. Jacobsite 
7. Poliauite 
8. Psilomelaue 
. (Fe,MQ)0.(Fe,Mu)203. 
. 3Mn304.2Fe203. 
. 9Mn2O3.4Fe2O3.MuO2.3CaO. 
. 3Mn203.MnS!03 to 4Mn203.MnSi03. 
. (Fc.Zn,Mn)0.(Fe.Mn)203. 
. (Mn,Mg)0.(Fe,Mu)203. 
. Mn02. 
. »i R"2Mn05 + n R"'4(Mn05)3; R"=Mii, 
Ba,K2, H2, etc.; R'" = Fe, Mn, AI. 
r — 
Crystalline. 
Strongly 
magnetic. 
Weakly or 
uon-magnetic 
_ ^ 
Non -crystalline. 
I 
8. Psilomelane. 
G.=3-7— 4-7 
Massive and concretiouary. 
r 
I. Mangan- 
magnetite. 
G— about 5 
Cubic 
(octahedral). 
2. Vreden- 
burgite. 
G.=4-74— 4-84 
Bronze 
tint in sun. 
Bronze tint. 
3. Sitaparite. 
G=4-93— 509 
Reacts strongly 
for iroa. 
r 
4. Braunite. 
G=4-5— 4-82 
Octahedral (tetragonal) 
and barrel-shaped crys- 
tals, sometimes twinned. 
Perfect octahedral 
cleavage. 
Black, bluish, or steel-grey tints. 
I 
Gelatinous silica 
residue. 
No gelatinous silica 
residue. 
f 
Containszinc. Contains no zinc. 
5. Franklinite. 
G=.'>-07— 5-22 
Cubic (octahedral). 
r 
6. JiiCobsite. 
G=4-75 
Cubic (octahedral). 
7. Polianite 
G=4-83— 50! 
Tetnigonal 
(prismatic). 
