30 



would become intermingled with, the hot solution of silica ; 

 and so be deposited with it in whatever fissure it was 

 poured into. It would thus appear as a mineral vein upon 

 cooling. 



The frequent appearance of gold in a finely divided state 

 and enveloped in iron pyrites can also be accounted for by 

 chemical action. When a solution of sulphate of iron comes 

 into contact with a solution of gold, the latter is precipitated 

 as a very fine powder of a dark colour, and the sulphate 

 decomposed. Gold would be dissolved by the chlorine of 

 the nitric and hydrochloric acids present or in its free 

 state, while the sulphate of iron would be formed by the oxi- 

 dation of the sulphide which is always so abundant. In this 

 way the invisibility of gold when disguised by iron pyrites can 

 be accounted for. But gold being volatile under very high 

 pressure, and at a high temperature, could also be sublimed 

 and condensed similarly to other metals which are conveyed 

 in this way. 



Besides the minerals, gold is found associated with remains 

 of the animal and vegetable kingdoms. These, though of no 

 commercial value, yet are of no less interest and importance. 

 By their means the age of the auriferous drift can be 

 relatively approximated, and when found over a large tract of 

 country they can be compared with one another. 



The animals whose bones and teeth are occasionally found 

 belong entirely to the past. They evidently must have been 

 of larger growth than is seen now. They comprise huge mar- 

 supials and immense birds. The fossil vegetable remains, as 

 leaves, fruits, stems of trees, etc., also indicate an ancient 

 flora that has almost entirely passed away. In a few instances 

 some modern genera resemble those that are found fossil 

 but only in a modified form. The majority of them belong 

 to extinct genera ; and all are of Tertiary age — probably 

 pliocene or even miocene. As these organic remains have so 

 frequently been found in auriferous alluvial drift, the miner 

 in these colonies is encouraged to proceed in his search when 

 he comes upon a layer of fossil leaves, fruits, etc., esj^ecially 

 if these lie beneath Tertiary basalt. 



During the pliocene period, this land must have been the 

 scene of intense igneous action, as is evidenced by the 

 immense flows of basalt that are met with throughout long 

 stretches of country. The course of the ancient valleys and 

 watercourses can be traced by observing the direction of the 

 basalt ; for as the semi-liquid lava would flow where there 

 was least resistance, it would naturally take the easy descent 

 down low-lying valleys and river-beds, and in this way they 

 can be traced for miles. The miner, then, should not be 

 discouraged or deterred from sinking by finding basaltic 



