1919.] The Sixth Indian Science Congress. elxxxi 
2. Manganese-ores. 
Turning now to the sedimentary mangarrese-ores, we find 
a belt of country extending from Jhabua in Central India 
through the Nagpur- Balaghat portion of the Central Provinces 
sometimes, as in the Nagpur district, exceedingly crystalline. 
Not infrequently, these rocks are cut by pegmatitic and 
granitic intrusions, which sometimes carry fragments of 
these exceptional minerals. On these Peon hs we are sale 
in concluding that a portion at least of the frequently highly 
crystalline gonditic ores are of pre-pegmatitic age, and on 
grounds of chemical composition and stratigraphical relation- 
ships, we are further justified in regarding them as representing 
braunitic ores (usually also carrying aie. whilst the 
less pure ores yielded the mixtures of braunite, 
result of segregative changes during metamor hism, 
assumed for the Lake Superior iron-ore formations, it is 
impossible now to say. 
1 Memoirs, Geol. Surv. is Vol. XX XVII, p. 306 (1909). 
2 AS 8 p. 5 (1911) 
3 Mem. G.S.1., XXXVII, p. 646 
6 336. 
