232 BROWN & HERON: GEOLOGY AND ORE DEPOSITS OF TAVOY 



such veinlets arc found in close association in soft ground they may 

 form a valuable source of these ores. Much of the .-o-: ailed "allu- 

 vial " concentrate won by sluicing residual or decomposed granite, 

 is derived from the very numerous stringers and mineralized cracks 

 penetrating the parent rock. 



Details of the strikes and dips of the veins are given in the de- 

 scriptive section dealing with the various mines, 

 Strike and dip. , .. , , . . , . 



and all that need be repeated here is that 



the general strike is north and south to north-west, south-cast, 



though there are m my exceptions to the rule. Dips are usually 



high, though veins with low angles of dip are also known. It has 



been asserted by some writers that the dips of the Tavoyan veins 



are generally inwards, towards the centres of the granite intrusions 



from which they have arisen; as a matter of fact there is very little 



evidence that such is the case. 



Composite veins are not rare and are to be found on nearly all 



the larger mines. They seem to point to the 

 Composite veins. ° ' 



tact that the fissure lines have continued as 



planes of weakness even alter a preliminary filling of vein matter. 

 Tims at Hermyingyij near the Waterfall, there is a composite vein 

 about 2| to 3 feet in thickness, the major part of which consists of 

 a hard, brittle quartz carrying wolfram. This is bounded on one 

 side by a band of shattered and weathered soft quartz full of impres- 

 sions left by pyrite crystals and containing poor wolfram values. 

 The foot wall of this part of the vein U shekeusided. Again, in the 

 Me-chaung section of the Tavoy Concessions Kyaukanya mine, 

 there is a heavily jointed vein, the central and major part of which 

 consists of a very pyritic and hard quartz. The boundary portions 

 on each side of the centre are made up of quartz which does not 

 contain any pyrite, but is full of small fragments of graphitic slate, 

 which were evidently torn from both walls of the country rock. 

 Both the vein and its walls show signs of much movement. These; 

 two examples, the first of a vein in granite, and the second of a 

 vein in the sedimentary series, will suffice to illustrate the fairly 

 common occurrences of composite veins. 



Bleeck's general description of the gangue quartz of the veins 



is a good one. He writes as follows : J — " It 

 Nature of tho vein c - n , •. -. , 



rtz is of a milky white and very compact appear- 



ance and lias a vitreous lustre on the fractured 



1 A. G. Bleeck (2), p. 65. 



