238 BROWN & HERON: GEOLOGY AND ORE DEPOSITS OF TAVOY 



absolute blanks, so that the original returns of over 8 per cent, from 

 picked ore have not been maintained. For reasons that need 

 not be enumerated, but which were unavoidable, the latest mill 

 returns have shown poor values, which, however, it, is safe to predict 

 will not continue. From careful consideration of the work which 

 has been done, the conclusions arrived at are that about two-thirds 

 of the lodes carry remunerative values, one-third representing the 

 blanks or unprofitable values, and that the average yield has been 

 ]J per cent., or 34 lbs. of wolframite per ton." 



Mr. J, Thomas, Government Mining Engineer, kept careful 

 data of the amount of ore mined and Concentrate won on a small 

 native-owned mine worked by tribute methods and employing 27 

 men. in the south of the district during the month of December 

 1917. These showed an average recovery of 2*25 per cent. For 

 the month of January 1918, a similar investigation on the same mine 

 gave a yield of 2*50 per cent. On another mine for the months 

 of November to February (1918) inclusive, the average yield of all 

 the veins was 21 per cent. From 50 observations made on the 

 relation of the size of the vein to its richness, the figures given 

 below were noted to be fairly regular on a small mine in Tavoy. 



Inches. 



1 per cent, veins averago width . . . . .12 



2 <> 



4 8 



5 ,, ,, ,, ...... (> and undor. 



Tribute extractions from four veins in the Paungdaw granite 

 region, representing several months" operations, were as follows : — 



Per cent. 



Vein No. 1 0-7f> 



„ „ 2 0-90 



„ „ :* i-oo 



„ „ 4 1-40 



Driving for 200 feet on a 1| foot vein in argillites on the wesl 

 bank of Tavoy river showed an average value by tribute methods of 

 1*90 per cent, and for 97 feet on another vein a return of 2"7 per cent. 

 was registered. 40 feet of driving on a third vein of an average 

 width of 9 inches yielded 1*10 percent. 



It is unfortunate that exact figures are not available regarding 

 the percentage of wolfram in the large veins of granite regions like 

 Paungdaw and llermyingyi. The estimates of those best acquainted 



