ON GOLD : ITS FORMATION IN OUR REEFS. 155 



3.— ON GOLD: ITS FORMATION IN OUR REEFS 

 AND NOTES OF SOME NEWLY DISCOVERED 

 REACTIONS. 



By William Skey, F.C.S., Analyst to the Geological Survey of 

 New Zealand, Wellington, New Zealand. 



I SEEK in this paper to discuss shortly the various prevailing 

 theories in explanation of the origin of gold in our reefs in 

 order that my own theory may be fairly considered. 

 I have divided my subject into two parts : — 



I. — Details of the evidence that I have gathered and experi- 

 mentally produced in the laboratory relative to the 

 deposition of gold in reefs. 

 II. — The various discovei-ies I have made relating to the 

 reactions of gold and the other noble metals when 

 subject only to ordinary atmospheric and terrestrial 

 agencies. 

 I. — Referring now to the first, it has been pretty conclusively 

 established that the material forming our reefs and also the gold 

 have been deposited from aqueous solutions. The most important 

 question, therefore, that now i-emains to be determined is, how 

 was its deposition accomplished 1 



Among the different theories that have been advocated, it will 

 be necessary to refer to the following : — 



a — That the reducing agent is one or other of the proto-salts 



of iron. 

 b — That it is organic matter, 

 c — That it is organic matter in conjunction with metallic 



sulphides. 

 d — That it is metallic svilphides alone. 

 a. That the reducing agent is one or other of the proto-salts of 

 iron. In regard to this hypothesis it cannot be doubted, that 

 they have at times, especially the sulphates and bicarbonates, 

 been concerned in the i^eduction of a part of our natural gold. 

 Gold reduced by these agencies would be finely granular, possibly 

 crystalline, but never so far as can be judged from laboratory 

 reactions, massive or even in nuggety grains. The bulk of our 

 gold is of a massive character, and we have still to find an 

 agent competent to depost it in this form. 



h. That it is organic matter. Organic matters easily decompose 

 the ordinary salts of gold, liberating it in the form of thin 

 laminaj or minute crystals, hence the popularity of the theory 

 that it is organic matter in a state of decay to which must be 

 ascribed the deposition of a large proportion of our gold. That 

 some gold has been reduced by this means is beyond dispute. 



