400 Transactions. — Geology. 



Art. XLVII. — A Theory on the Fonnation of Gold into 

 Specks and Nuggets. 



By H. P. Washbourn. 



[Read before tJic Nelson Philosophical Society, 16th September, 1889.] 



In this paper I shall open the question, How is gold 

 formed into specks and nuggets ? and also dispute the theory 

 that alluvial gold was not derived from reefs, but was formed 

 in the drift in which it is found. This, I consider, is a theory 

 as yet quite unsupported by any facts, as the reasons relied 

 on to establish it are quite untenable. 



If the gold were deposited from solution as a dark impal- 

 pable powder, how did it get into the quartz in the shape of 

 specks and nuggets, in which it is found ? This is a question 

 I have often heard asked, but I have never heard or seen it 

 answ^ered. 



In accounting for it, we must quite put aside the idea that 

 the reefs have been molten, and that the gold has been melted 

 into the shapes in which it is found. There has never been a 

 reef found with evidence of its having been formed by molten 

 matter ; but, even if there had, it would not account for the 

 w^ay the gold is found in the many reefs that evidently have 

 not been affected by heat. The heat necessary to melt quartz 

 is so great that it would have changed the character of the 

 rock forming the walls of the reef, with which the molten mat- 

 ter must have been in contact ; and the other minerals found 

 in the quartz in masses, and crystals containing such volatile 

 substances as sulphur, arsenic, antimony, &c., must have been 

 altered, and the volatile portions driven off by the intense 

 heat. 



But the walls only show the action of water, and in the 

 hard quartz we find perfect crystals of minerals that less than 

 a red heat would destroy : yet these are perfect ; and the hard 

 quartz surrounding the crystal takes the exact form of it, 

 showing that the quartz was soft when the crystal was formed, 

 though not molten. 



Beyond doubt the gold was carried into the reefs in a solu- 

 tion by water, and, meeting with a reagent, was precipitated as 

 a powder, the particles of which were as fine as or finer than 

 anything we can conceive, and this was deposited on and with 

 silica in a soft state. There are several reagents that will 

 precipitate gold from solution, such as sulphateof iron, formed 

 by the decomposition of iron-pyrites, vegetable matter, &c., 

 and I think it very probable that in the same reef the gold has 

 been precipitated by different causes at various parts and 



