Ixxiv 
AfAliGANESE DEPOSITS OP INpr,4. 
[ Part ii.] 
[ GEOLOGY.] 
Mode of Occurrence and Origin.) 
[CHAPTER XI.] 
General. 
A brief accouut is given of the Archaean rocks of the Indian 
Peninsula, and the following classification of the Indian pre-Cambrian 
rocks is adopted : — 
I. Archaean : — 
1. The oldest gneisses (Bengal Gneiss). 
2. The schistose gneisses and the Dharwars. 
3. The plutonic intrusives, such as the Bundelkhand granite 
and the charnockite series, 
II. Purana : — 
The Bijawars, Kadapahs, \'indhyans, etc. 
The occurrences of manganese-ores and minerals in India are 
classified according to the age of the rocks with which they are 
associated, although they have in many cases been formed by secondary 
processes subsequently to these associated rocks. All the ores at 
present being worked are associated with rocks of Archaean age, with 
two exceptions. Those of Archaean age are divided into three main 
groups : — 
1. Those associated with the rocks of the kodurite series of the 
Vizagapatam and Ganjam districts, Madras. 
2. Those associated with the rocks of the gondite series of the 
Central Provinces, and Jhabua, in Central India. 
3. Those occurring as lateritoid on the outcrops of rocks 
of Dharwar age, in Belgaum, Jabalpur, Mysore, Sandur, 
and Singhbhum. 
The two exceptions are those ores that can be regarded as occur- 
ring in true laterite — though this is very closely related to lateritoid, — 
