Chap. XLT. ] 
SHIMOGA : BiKONHALLr. 
1141 
A rough analysis of this dolomite by Mr. Fawcitt showed : — 
CaCOa 48-35 
MgCOs. . .... . . . 34-70 
Fe^O and AI3O3 5-10 
Mn-iOi . . . ■ 1-87 
8ilioeou8 matter ....... 10-10 
100-12 
The chief manganese-ore is pyrolusite, whilst the chief iron-ore is 
limonite, sometimes in the form of yellow ochre, 
thf ^""^ °* but more often in the form of the dull hard 
variety. This is often traversed by veinlets 
of pyrolusite, which, La cavities, pass into very pretty aggregations of 
pyrolusite crystals of considerable perfection, but small size. Along 
cracks the limonite often forms mamniillated radiate layers, and in 
places this limonite seems to be darker than usual and to be highly 
manganiferous ; but it is not quite certain that the manganiferous 
character of the limonite may not be due to some minute shining specks 
that are sparingly scattered throughout it. Sometimes concretionary 
psilomelane is also found along cracks. There is also a little of the 
hard grey crystalline mineral (?polianite ; see below). 
As might be expected from the mode of occurrence, the ores are very 
siliceous, and it is doubtful if any system of cleaning, except 
crushing and washing, could bring down the silica to a small figure, with- 
out enormous loss of ore. The following three analyses by Mr. Fawcitt 
give some idea of the chemical character of the ores : — 
No. 1. 
No. 2. 
No. 3. 
MnOj 
76-03 
88-03 
MnO 
1-74 
3-74 
Fe^O, 
13-60 
2-96 
Al,03 
2-06 
2-04 
CaO 
1-18 
1-03 
MgO 
0-76 
0-68 
Alkalies ........ 
trace 
trace 
SiO^ 
3-62 
1-24 
9-66 
Combined water ....... 
1-CO 
0-37 
90-99 
10009 
IV 
M 5i 
