GEOLOGY AND PETROGRAPHY OF THE PROSPECT INTRUSION. 533 



across the middle of the picture from top to bottom are 

 these : — 



Coarse pegmatite 



15 cms. 



6 inches 



Fine pegmatite 



2*5 „ 



i „ 



Pine and medium aplite... 



7'5 „ 



3 „ 



Fine pegmatite ... 



2 „ 



Of „ 



Coarse pegmatite 



35 „ 



m ., 



Approximate total width 62 „ 24 ,, 



A photograph of the lower great vein only a few metres 

 from the part just described is reproduced in Plate 

 XXXVIII. Measuring across the vein it is composed as 

 follows : — 



Pegmatite ... 7 inches. 



Medium aplite ... 2 ,, 



Coarse aplite f to £ „ 



Medium aplite ... 2\ ,, 



Pegmatite ... 3 „ 



Total 14f „ 



The specimen shows the full width of the whole vein at 

 this point. As usual the aplite occupies the middle of the 

 vein. A vein containing aplite only will be seen branching 

 downwards at the left of the photograph. This vein con- 

 tains medium aplite and is about \\ to 2 inches in thickness. 



A specimen of fine-grained aplite, with a vein of coarse- 

 grained aplite traversing it is, reproduced in Plate XL. 

 The aplite is light greyish-green in colour, the individual 

 crystals of felspar are just visible with the naked eye, and 

 the fracture is rather rough. In general appearance it 

 reminds one rather of a solvsbergite, but the green 

 colour is not so bright, being chloritic. The vein of 

 coarse-grained aplite has sharply defined and irregular 

 boundaries. Opposite edges do not fit into one another, 

 either on this side or on the reverse, hence the vein is 



