elxxx Proceedings of the Asiatic Society of Bengal. [N.S., XV. 
noteworthy components of the Archaean terrane in many parts 
a satisfactory solution of the difficulties in reat pei with 
heir origin in one part of the world s prove very 
useful in solving the problems connected with | similar rocks in 
other parts. Although these silica-iron-ore rocks and associated 
iron-ore deposits occur in great abundance in various parts o 
India (e.g. Singhbhum, Mysore and Salem), nevertheless the 
) 
e 
boring operations that would enable us to draw 
conclusions as to both the origin and extent of these deposits, 
or 
summarising the results of the Sawin. (extending over many 
years) of Von Hise, himself, and their co-workers', these rocks 
were originally deposited as a series of aqueous sediments, 
rtly as cherty iron carbonates, partly as ferrous silicates, 
ri 
chemical changes due to the influence of waters carrying 
oxygen and carbon dioxide, the iron as oxide and the silica 
have segregated from each other, with various results according 
to the structural conditions and subsequent tectonic history o 
each case, the resultant rocks being ferruginous cherts, jaspers, 
amphibole- -magnetite-schists, and iron-ore bodies, all of which 
types of rock are found in India 
In Singhbhum and Orissa large bodies of hematite 
have been yeas recently along a high range extending 
for some 40 miles in a S. 8. -W. direction. Enormous —. 
of these ore-bodies to the deep can safely be made in’ advance 
of the results of diamond drilling. 
At the surface such ore-bodies, which are usually composed 
of hemnsite, my often found to be 
hydrated, Singhbhum and Goa, 
with production of a limonitic ee ing, ‘uiiadiately below 
which lies the compact hematite. Such development work 
as has yet been done in Singhbhum and Goa indicates, however, 
that below the com pact hematite lies friable micaceous 
aa and it is a matter of great practical interest to 
Surface modifications. 
1 erie: Amer. Inst. Min. Eng., Vol. XXXVI, pp. 101- 163 (1005). 
