MINING PRACTICE. 



83 



lenses and stocks. The system was adopted by Mr. E. H. Sargent at 

 Inikurti, the first mine successfully worked, and the success attending 

 Mr. Sargent's work has led to imitators in other plots where the condi- 

 tions are less favourable. Inikurti, however, is a most exceptional 

 instance, the pegmatite stock being some 300 feet long and 150 feet 

 wide, with the quartz forming a large boss in the centre and the mica 

 and felspar disposed in a horse-shoe shaped zone around (fig. 18). 



Waste 



Waste 

 heaps 



Waste 



heaps 



-* c °vered *$* 



Fig. 18. Plan of the IniMrti quarry, December i8gS. 



Scale, 1 inch = 100 feet. 

 Levels, + above, and — below, the surface of the plain. 



Nevertheless, Inikurti is now reaching a stage where the expense of 

 working is gradually encroaching on the revenue obtained from the mica 

 raised ; for the sides of the open quarry, with the large masses of waste 

 piled around, are slipping back into the quarry as fast as the bottom is 

 being lowered, and the system which has allowed a sufficient margin of 

 profit in the past will have to be substituted for a more rational 

 organization in the future. 



With a wide open quarry already made, the adoption of a system of 

 shafts, cross-cuts and drives may be found inconvenient, and the sides 

 of the quarry having extended back, in practically all such cases, by 

 falling in during work, there will always be considerable trouble 



( 73 ) 



