Washboubn. — On the Forynation of Gold. 401 



periods of its formation, and that, like most things in nature, 

 a reef, with its minerals, is the result of a combination of 

 many causes, of which, although there are a few we do know, 

 there are a great n\any we do not know as yet. 



The atoms of precipitated gold, having a very strong attrac- 

 tion for each other, would gradually draw together, forming 

 minute specks, which would also be drawn towards each other, 

 forming larger and irregular specks as they joined, until the 

 hardening of the quartz prevented any further movement. 



The time taken by quartz in hardening would probably 

 vary in different reefs, and also at different times and places in 

 the same reef. Where the hardening has been slow the gold 

 would be coarse, and, if a flat reef, towards the foot-w^alls, as 

 its great specific gravity would give it a downward tendency. 

 Where the gold-precipitate was evenly distributed with the 

 silica, and the hardening of the quartz was not very slow, the 

 gold would probably be in fine specks through the stone, as 

 there would only be time for the contiguous atoms to join 

 before the quartz became too hard for further union. We can 

 see by the hot springs in the North Island that when silica 

 has been held in solution in hot water it hardens much 

 more quickly than when the water is cold. 



At the Thames and Te Aroha, where the hot springs have 

 evidently played a part in the formation of the reefs, we find 

 the gold in very fine particles ; and I suspect that a good deal 

 of the gold (not recognizable as such, and) said to be an ore of 

 gold is really the gold as precipitated, the quartz having 

 hardened too quickly for the atoms to join together to form 

 specks. We must bear in mind that gold is only yellow by 

 reflected light, and that in a state of fine division it is simply 

 a dark powder, and would look like an ore. 



It is very common in quartz-specimens to get what is called 

 a nest of gold, which generally consists of one large speck 

 surrounded by a number of smaller ones at various distances 

 from it. These, I believe, are a number of atoms attracted 

 together, gathering and joining other particles as they are 

 drawn towards the centre; and if the quartz had remained soft 

 long enough they would have joined the centre one at different 

 points, forming one large irregular speck. If we consider the 

 great ductility and malleableness of gold, we shall not be sur- 

 prised at the powerful attraction the particles seem to have 

 for each other, as those qualities are due to the cohesive at- 

 traction of the atoms of which it is composed ; and if this is 

 so great when near together it does not seem unreasonable to 

 expect that when separated by a short distance the same 

 power should exist, although perhaps in lessened degree ac- 

 cording to distance. A certain degree of heat seems to increase 

 this. I have often seen with alluvial gold, when heated a good 

 26 



