338 BROWN ft HERON GEOLOGY AND ORE DEPOSITS OF TAVOY. 



regarded as magmatie by those who believe in the versatile efficacy 

 of igneous processes in mineral formation and deposition." 3 



It is our belief that the wolfram-eassiterite-sulphide deposits 

 of Tavoy district were formed partially under conditions closely 

 allied to strictly magmatie ones, were also formed by processes in 

 which gaseous agencies, including compounds of fluorine and sulphur, 

 to some extent played a part, and, in rarer cases, by hydrothermal 

 reactions which followed as a consequence of the former ones. [t 

 is impossible to draw any hard and fast lines between the different 

 stages, which are all part of one continuous process, doubtless 

 proceeding concurrently in some cases. In foot the whole process 

 of mineral vein formation associated with the great granite chain 

 extending from the southernmost limits of Burma to an unknown 

 termination in the Shan States, as far as we have examined it at 

 present, appears to be a direct sequence of processes of differentiation 

 or fractional crystallization through a series of varying phases 

 induced i n the original magma by decreasing temperature. 



1 L. C. Grafton and D. H. McLaughlin, l.oc. cil. pp. 83-80. 



