210 BROWN & HERON: GEOLOGY AND ORE DEPOSITS OF TAVOY. 



in size from small pieces a few inches in diameter to great masses 

 of several hundredweights. Inteigrowths of quartz are always 

 found in the larger pieces. Characteristic of the crystals are the 

 corrugations and striatums of the prismatic faces, parallel to their 

 length . 



The mineral also occurs in massive, lamellar, divergent or 

 radiated, columnar and acicular forms. It is better to mention 

 examples of each of these than to attempt a general description of 

 them all. 



(1) Massive wolfram. In its typical condition this is found in 

 small veinlets of almost solid mineral penetrating sedimentary 

 rocks or in the rather larger ones cutting through granite and greisen. 

 The former type is well illustrated by specimens from Mr. T. Fowle's 

 Yanmazu mine where stringers of nearly solid wolfram about | of 

 an inch in thickness occur. On fractured faces the coarsely crys- 

 talline structure is evident. Mica and a little quartz are the only 

 other minerals. 



The second case is illustrated by specimens from the Taung- 

 shuntaung mine of Messrs Ady, Giles and Hossein Amadanee. 

 Here veinlets in greisen are 2\ inches thick, consisting of wolfram 

 on the walls and cassiterite in the centre with irregular veinlets 

 and small pieces of quartz. Polished surfaces show the coarsely 

 crystalline structure of the mass and recall that of cooled molten 

 metals. Weathered surfaces exhibit an irregular appearance due 

 to the unequal resistance of individual crystals. 



Weathered surfaces of a specimen of massive wolfram from 

 the Ye subdivision of Amherst district have a roughened, rounded 

 appearance similar to that displayed by certain iron and manganese 

 ores under the same conditions. 



(2) Lamellar forms. Thin lamellae of wolfram are found in 

 argillites near the veins in the Yewaing section of Crisp and Com- 

 pany's Pagaye property. Their surfaces often show iridescent 

 colouring. This is also seen occasionally on the more massive 

 forms, which are termed u rainbow wolfram " bv miners. 



(3) Divergent and radiated forms. These are the commonest 

 types throughout the field and may consist of coarse individual 

 growths up to an inch in thickness, down to quite small and closely 

 packed fibres which recall the structure assumed by schorl. Espe- 

 cially characteristic are the various angles from which each group 

 of individual fibres commences and the curving of the fibres which 



