STRUCTURES AND CHARACTERISTICS OF TUNGSTEN DEPOSITS. L >33 



surfaces. In some localities it is honeycombed and iron-stained 

 along the outcrops, notably so at Kadwe. Very often the 

 quarts shows numerous little cracks and veinlets containing red 

 oxide of iron. Microscopically the quartz contains numerous 

 vesicular inclusions. The extinction is undulatory.** 



In the larger veins the quartz is of a i; blocky " nature and tends 

 to separate into large roughly cubical masses. Along these part- 

 ings and joint planes there arc often black and brown films of iron 

 and manganese oxides. Small irregular vugs and hollows sometimes 

 occur, filled with the same compounds, remains of pyrite cubes and 

 crystals of ferrous sulphate Veins containing large geodes and 

 crystals of quartz arc very exceptional, but they do occur at Kan- 

 bank. Jn some of the smaller veins which traverse granite the gangue 

 quartz often assumes a more glassy appearance than it docs in the 

 larger ones. 



Mica is an almost invariably associated mineral in the veins. 



It occurs in small flakes, as thin bands along 



Mica of the veins and } „ s d ■ gba] aggregates in the quartz 



itself. The commonest variety is muscovite 

 in silvery white or yellowish flakes. Green chlorite is also common. 

 According to Bleeck, 1 lithia chlorite has been observed, in which 

 the presence of lithium can only be detected chemically. Reddiah- 

 brown micas, which often occur in the greisens, notably at Wagon 

 South and in Paungdaw, may be lithium-bearing, but this group 

 of minerals needs further chemical investigation. Thin bands of 

 a ffreen mica-rock are also found in greiscn at various localities. 

 The erratic distribution of wolfram in its parent veins is an 

 exceedingly well-known phenomenon, and Tavoy 

 JuJ^ZZ!:- ! does uot dill,,- from othsi wolfram Balds 



of the world in this respect. In the most ex- 

 treme cases massive slugs of wolfram, up to a ton in weight, have 

 been found in quartz veins, but any profit which has accrued to the 

 miner from them has generally been lost in driving through barren 

 "round to find the next one. In this connection it is our experience 

 that veins in which small scattered crystals of wolfram occur, arc 

 generally more uniformly productive than those in which larger 

 masses are found at irregular intervals. The question whether 

 wolfram does or does not occur in (i shoots " is one of considerable 



1 A. G. Bloock (2), p. US- 



