Geology 



against the banks of gravel. The water and the material 

 thus washed down was then led through shallow troughs 

 in the bottoms of which a number of grooves had been 

 cut from side to side. 



The quartz and other light minerals together with 

 the finest of the gold-dust were carried away by the 

 current while the coarser particles of gold were caught 

 in the grooves and removed from time to time. 



The tail waters from this arrangement were led 

 through a second series of sluice-boxes in which the 

 grooves were filled with mercury. 



Gold being heavier than mercury, the fine dust 

 which escaped from the upper boxes, of course, sank 

 into the quicksilver, while the sand being lighter, re- 

 mained on its surface and was washed away the gold- 

 dust dissolved in the mercury forming an amalgam from 

 which it was recovered by distillation, the mercury being 

 condensed and collected for further use. 



In this way the finer part of the material washed out 

 by the water jets was dealt with, but the coarser gravels 

 brought down by the same process had to be handled 

 with shovels and picked over by hand. A few small 

 nuggets were thus obtained, but they formed but a small 

 percentage of the total yield. 



Some of the quartz pebbles which contained gold 

 were put aside for subsequent treatment when a battery 

 of stamps, now on its way up the river, should have 

 arrived and been set up. There was no difficulty about 

 power, as the Centre Valley River, though inadequate 

 for hydraulic mining owing to lack of fall, was yet amply 

 sufficient for working turbines. Indeed, a central electric 

 power station and distributing apparatus had already 



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