1919. ] The Sixth Indian Science Congress. elxxxvii 
duction of valuable minerals into rocks of Dharwar type. 
It may well be asked how is it that, considering the vast area 
or Peninsular India occupied by ‘Are aean granitic gnei 
a 
Co omparative scarcity of 7 2 
Asihacich aoismabies ake mot are so scarce? The answer 
deposits in India. 
either in Dharwar schists or in vce cataniasd gre Meorbhy have 
posits, or, if so, that the conditions of solidification were 
favourable to the concentration of these constitue on aes 
ore-bodies. But there may be another vey good r 
We have already eee a that a considerable piel 8 
the ‘‘fundamental gneiss” of India may be an older pre- 
Priva a 4 Dig cvar gneiss re-melted so as to 
granites.» CP pear now as a later intrusion. This 
old ; doubtless lost its mother- 
nia metalliferous contents, and mineralising agents, at 
the time of its original solidification. Re-fusion could not put 
these constituents back into the magma, except in so far as 
porti 
re-melted and assimilated in the granitic magma, This con- 
sideration means that, whereas Wwe may expect a primary 
or virgin granitic magma to produce mineralisation of the 
rocks into which it is ae we can hardly expect this 
of a secondary or re- inated ek 
In addition to the penal ser ore-deposits discussed in — 
section of my paper, there i 
d Sea ee siderable number of small sppvaite of 
copper, lead, gold, etc., scattered over 
the Archaean terrane of India. It will be of interest in the 
future to determine the extent to which these deposits are to 
be regarded as due to post-Dharwar granitic intrusions and 
the extent to which they are in any way related to the suggested 
re-melted gneisses. Some of these deposits, particularly some 
associated with silicate minerals such as garnet, diopside and 
‘tremolite, in such a way as to suggest that they may be con- 
tact-metamorphic deposits ; if so, future research may point 
to the necessity of establishing a eee of the epigenetic 
. deposits to — such occurren 
_ Let us now discuss in turn pin of the three areas Singh- 
bhum, Sikkim, and Kolar. 
