Chap. XXIV.] nomenclatttre of manganese-oees . 
499 
a given area to be usually somewhere about 60%. Then the following 
classification would seem to be a rational one : — 
Mn . per cent . 
Fe per cent. 
Manganese-ores ..... 
4o-bU 
0-15 
Ferruginous manganese -ores 
30-45 
15-.30 
Manganiferous iron-ores .... 
15-30 
30-45 
Iron-ores ...... 
0-15 
45-60 
Although the sum of the Mn and Fe in the ores of the Central Provinces 
is usually nearly 60%, yet there are many cases where the sum of these 
two constituents is considerably less than this amount. A reference 
to the table on page 512 will show that the sum of these two constituents 
in the average ore of different areas in India varies from 46* 77 (Singh- 
bhum) to 59 "80% (Chhindwara). For ores in which the sum amounts 
to 52% the nomenclature wotdd be as follows : — 
Wn. per cent. 
Fe per cent. 
Manganese -ores ..... 
3 £-52 
0-13 
Ferruginous manganese-ores 
2e-39 
13-26 
Manganiferous iron-ores .... 
13-26 
26-39 
Iron-ores ...... 
0-13 
39-52 
Similar sets of figures could be drawn up for any other value of Mn -|- 
Fe, by dividing the Mn and Fe percentages into four equal sections. 
In the tables of analyses of Indian ores given on pages 501 to 513, I 
have used this principle in classifying the ores, extending, however, the 
class of manganiferous iron-ores in accordance with the next paragraph. 
For commercial pui-poses, however, one table for all ores would pro- 
bably be considered desirable. Hence to allow for the facts, (i) that ores 
