MINING PRACTICE. 8l 



mine was opened near the summit {C, fig. 17) of a steep-sided, roughly 



Fig. 17. Plan 0/ hill showing the outcrop of a pegmatite-sheet, and section 

 of the same in the direction of dip. Scale, 1 inch = ioo feet. 



conical hill, and followed as a slightly tortuous hole for 115 feet at an 

 angle of 45 , almost exactly in the direction of true dip of the schists 

 and that of the included pegmatite-sheet. The pegmatite was originally 

 discovered at the summit of the hill because it had been laid bare by 

 weathering, and it never occurred to the manager of the mine that the 

 same sheet stretched obliquely through the hill with a continuous out- 

 crop on either side, merely hidden by the thin layer of loose rubbish and 

 vegetation (fig. 17). The whole of the materials— mica, rubbish and 

 water — were handed up by a string of 80 cooly women to the mouth 

 of the pit (C), whereas for a very small fraction of the working expense, 

 the pegmatite vein might have been attacked on the flanks of the hill, 

 the materials brought out by trams along gently sloping drives (A. M. 

 and B.M., fig. 17) and the drainage problem allowed to settle itself by 

 natural flow of the water along the same adit. 



( 71 ) 



