290 Proceeding)^ of the Royal Sociefi/ of Victoria. 



was "rubbly." When solid ground was reached there was often 

 a sudden and serious dwindling of the yields. In such cases the 

 gold about the out-crop might represent the contents of many 

 feet of the lode above the present surface of the ground. 



Secondly. — Chemically, by the action of rain-water percolating 

 through the strata and draining into the lodes and along them, as 

 the easiest course, to lower levels. Such waters and the air acted 

 on the sulphides, decomposing them, and in turn charged with 

 the products of decomposition dissolved some of the gold, and 

 bore it away to .some other portion of the lode where the 

 conditions were favourable, and there the gold was re-deposited. 

 In this way some lodes have become enriched in their lower 

 levels by gold brought in solution from the higher levels. 



Rich ore has often been found in quartz reefs just above water 

 level. From the appearance of the gold in the quartz in many 

 cases enrichment might be inferred, for the gold appears to have 

 pushed the quartz apart as it increased in bulk in the cracks and 

 fissures until the stone has a crushed appearance. Cases of this 

 have been observed at Maldon, Sitlington's Mystery Reef, near 

 Elaine, at Tangil and elsewhere. That gold was deposited 

 subsequent to the deposition of the quartz in some cases is fully 

 proved by instances that the writer met with in West Australia. 

 A nugget weighing over 90 ozs. was seen that had evidently been 

 formed in a cavity lined with quartz crystals, for it retained 

 sharp hollow casts in its substance of quartz crystal pyramids. 



For the self-same reason that portions of auriferous quaitz- 

 lodes above the water level may become enriched by gold 

 removed from some other portion of the same lode, the portion 

 of the lode above water level may, and does, often represent a 

 zone of impoverishment. This must be the case at the Caledonian 

 Lead, where gold dissolved from the Caledonian and Devonshire 

 Reefs finds its way into the channel of the Devonian Lead. 



Cases are common in Victoria where highly aurif<-rous lodes are 

 cut across by a fault, and beyond the fault the lode is barren, or 

 nearly so. In such cases one explanation may be that the 

 fracture has opened a means of surface drainage by which the 

 gold has been leached out of the barren sections of the lode. 



On the lateral seci-etion theory of lodes the Caledonian Lead 

 occurrence has also a bearing, for where the walls of lodes or the 



