A u rifero us Quartz - vein s . 
127 
To judge by the extraordinary richness of many of our alluvial 
workings, and the size of the nuggets found in them, as compared 
with the yields obtained from the auriferous quartz reefs near 
them, the conclusion suggests itself that the denuded upper por- 
tions of those reefs, whence the alluvial gold was originally derived, 
must have been far richer than what remain intact, oven allowing 
for the denudation of the Palccozoic rocks and their associated 
quartz-veins, for a thickness of many hundreds or even thousands 
of feet in vertical height above the present surface, and the con- 
centration of the gold thus disintegrated into gravelly deposits of 
comparatively limited extent. With the fact of our surface 
quartz having so far proved of greater average richness than that 
obtained from considerable depths,* and the strong evidence that 
the quartz which has been denuded, and from which the gold of 
the alluviums has been disintegrated by geological action, was 
oven richer still, the general correctness of the first portion of the 
opinions referred to remains unchallengeable, though enough has 
fortunately been proved to justify sanguine hopes ns to the future 
progress of deep quartz mining, and to warrant the expenditure 
of capital in its development. 
* The quartz-mines of Sandhurst afford a notable exception to this rule. 
