celxxxii Proceedings of the Asiatic Society of Bengal. [N.S., XV, 
Mention has been made of the action of waters carrying 
oxygen and carbon dioxide in effecting a re-arrangement and 
concentration of iron in the Lake Superior iron-ore deposits. 
ention has also been made of the surface hydration of 
Surface modifications, dian Dharwar hematite bodies with 
formation of limonitic cappings. alo- 
gous cases of surface hydration of gonditic manganese-ores 
are rare,' but there is one very interesting case of surfac 
modification worthy of special notice. The manganese-ore 
braunite, with three minerals new to science,—hollandite, a 
complex manganate now found to be a crystalline form of psilo- 
One other aspect of the gonditic ore-deposits deserves 
mention, viz. the progressive increase in the phosphorus con- 
tents with increasing depth being experienced in practically all 
the manganese mines of the Central Provinces; the cause of 
this increase is at present unknown. I , as seems possible, the 
low phosphorus contents of the surface ores is due to surface 
leaching of the phosphorus compouud (? apatite), then the 
: aes Nagpur district, is a good example. See l.c., p. 949. 
C., p. 785. 
§ G. H. F. Smith and G. T. Prior, Mineralogical Magazine, XVI, 
p. 84 (1911). 
