STRUCTURES AND CHARACTERISTICS OF TUNGSTEN DEPOSITS. 237 



content which need from eighteen to twenty-four men to produce 

 the same yield of concentrate." An example is given of mining 

 operations conducted for eight months on narrow veins varying 

 from 0*58 to 1*83 feet in thickness in which the recovery was 1*28 

 per cent, of quartz broken. These, of course, are tribute results 

 gained under a system which wastes anything from 25 per cent, to 

 50 per cent, of the values. The same writer points out that the 

 number of 1 per cent, propositions is relatively small compared with 

 the high grade mines which earn large profits on from 2 per cent, to 

 3 per cent. ore. 



H. D. Griffiths 1 writes: — <c The writer has seen most of the 

 important wolfram lodes of Burma, and from evidence gathered. 

 and from the quantity of ore now being extracted, has come to the 

 conclusion that the decomposed zones of the lodes carry high re- 

 munerative values. They also carry blanks or poor patches like 

 all the similar deposits, but the richer portions are sufficiently 

 good and extensive to make a good average. As an instance can 

 be mentioned the case of a number of lodes having been mined to a 

 depth exceeding sometimes 150 feet, and the ore being milled after 

 a small amount of sorting had been done. The work extended 

 over five years, 31,000 tons being milled for a return of 12 lbs. per 

 ton (or 1 "87 per cent.). The rejected dumps on testing proved to 

 have a value of 11 lbs. per ton (or 0*49 per cent.), and were eventually 

 crushed in the mill at a profit. The tailing, owing to shortage of 

 water and imperfect concentration, assayed from 7 to 8 lbs. per ton. 

 Some lodes in Burma will assuredly yield more than the value 

 above quoted, and so far as is known few lodes have proved entirely 

 barren. In another case that came under the notice of the writer, 

 1,000 tons of quartz, obtained by driving on five lodes, on being 

 roughly sorted and hand-crushed, yielded 50*4 lbs. of wolframite 

 per ton (2*25 per cent.). 



Regarding Kanbauk, Mr. Griffiths 2 writes: — "Previous to the 

 installation of a crushing plant, all the crushing was done by hand, 

 such portions of the lodes only which carried wolfram in large 

 quantities being treated, the remaining quartz being thrown out 

 on the dumps. On completion of the crushing plant all the quartz 

 mined, together with a large portion of the old dumps, was crushed, 

 the only portions of the lodes left in the stopes being those showing 



1 H. D. Griffiths (12), p. f>4. 

 J H. D. Griffiths (13), p. 213. 



