CHAPTER VIII. 



THE ORIGIN OF THE WOLFRAM AND CASSITERITE ORES OF 



TAVOY. 



Earlier writers.— A. G. Bleeck, 1913. y —k. G. Bleeck, writing in 

 1913, was the first geologist who attempted to classify the wolfram 

 and cassiterite deposits of Tavoy and to give an account of their 

 origin. He divided them as follows : — 



(1) wolframite-quartz lodes. 



(2) cassiterite-quartz lodes. 



(3) wolfram greisen. 



The wolframite-quartz lodes are stated to be the most important ; 

 of the other two classes only a single example of each was observed. 

 The writer refers to the district as a wolframite-cassiterite-columbite 

 zone. " Judging by the petrological and chemical evidence detailed 

 above, there appears to be little doubt that the ore bodies of the Tavoy 

 district indicate a distinct mineral zone, this term being used in a 

 parallel sense to that of petrological province. This mineral 

 zone is characterised by the persistent occurrence of the mineral 

 columbite. In other parts of the district, which were not visited 

 by me, tin ores perhaps predominate over wolfram ores, and in a 

 broader sense and applied over larger areas, the mineral zone might 

 be termed a wolframite-cassiterite-columbite zone." Again, " Col- 

 umbite in black orthorhombic crystals, was observed in all the lodes." 



These observations have not been confirmed. Niobium has 

 been reported to occur in minute quantities in some wolfram con- 

 centrates from Tavoy, but the form in which it is present is unknown. 

 The oxides of niobium and tantalum have also been proved in small 

 quantities in wolfram from various localities in the United States 

 and other countries, but free columbite or tantalite has never been 

 found in a wolfram-bearing pegmatite or quartz vein in Tavoy, 

 either by ourselves or anyone else that we are aware of up to date. 



Bleeck's observations regarding tourmaline and flourite have 

 also to be corrected in the light of more recent research. " Tour- 

 maline," he writes, "is present everywhere, generally in micro 



1 A. G. Bleeck (2), pp. 48-73. 



