402 Transactions. — Geology. 



deal below red heat and shaken, the specks of gold would 

 adhere firmly together — sufficiently so to remove them from 

 the sand — and then fall apart as they cooled. If the gold 

 formed into specks in the quartz by the attraction of its atoms, 

 so did the pyrites, crystals, &c., by a similar process before 

 the quartz hardened. At the Parapara, ironstone pots or 

 bombs can be seen in all stages of formation, from the first 

 rough outline, enclosing a quantity of iron-containing earth, to 

 the highly metallic shell enclosing the earth from which every 

 particle of iron has been attracted to form the pure-iron- 

 looking bomb. 



lu his "Chemistry of the Goldfields" Professor Black men- 

 tions a theory originating with Mr. Selwyn several years ago; 

 and the question is put in this way : "Do nuggets grow ? " Of 

 course, the growing must be understood to mean an increase 

 of size by the addition and cohesion of atoms of gold. In this 

 way I think they undoubtedly do grow ; and if a flow of water 

 carrying gold in solution — but not silica — were to pass along a 

 lode under favourable conditions for deposition for a sufficient 

 time they might grow to any size. But, in an ordinary way, 

 the water carrying gold in solution does carry silica with it, 

 which, being deposited and hardened, prevents further union 

 of the gold atoms, thus limiting the size of the nugget and 

 forming a reef. The exceptional ones, carrying gold in solution 

 without much silica (or not depositing it), allow the gold to 

 accumulate in the favourable places for its deposition as 

 excrescences on the walls, or vughs, in the watercourse. 

 Although I agree that nuggets do grow, I do not think there 

 is evidence of their having done so in the drifts or washes, 

 the strongest arguments brought forward in support of the 

 theory only tending to show the possibility of it. The follow- 

 ing are the chief arguments used in favour of the theory that 

 alluvial gold has grown in the drifts : — 



1. " Nuggets are found in the alluvial drift of larger size 

 than any piece of gold ever got from reefs." In answer to 

 this we must consider the very small amount of quartz reefs 

 that have been broken up and worked by man, as compared 

 with the immense quantity broken up by Nature and forming 

 the drifts. The difference is so immeasurable that the com- 

 parison is absurd. 



2. " That alluvial gold is of a higher quality than reef -gold 

 from the same neighbourhood." This is said to be a very 

 strong argument, but I consider it requires very careful 

 investigation before it is taken as a fact. I do not admit that 

 the statement is correct as a rule, and I will mention two 

 cases to show why : First, in Bedstead Gully there were two 

 distinct qualities of alluvial gold — one a rough honeycomb 

 gold, derived from the reef at the head of the gully, and of the 



