152 ORIGIN AND MODE OF OCCURRENCE OF GOLD-BEARING VEINS. 



galena, sulphite of silver, sulphite of antimony, and sulphate of 

 bismuth. Electricity is shewn to be capable of creating fissures 

 and filling them with metals by an experiment made by Mr. R. 

 W. Fox, who produced fissures in clay and filled them with metallic 

 substances by means of electrical currents generated artificially. 



Water under heat and pressure has been shewn to dissolve or 

 decompose certain minerals and redeposit their constituents or 

 some of them in other mineral forms. 



Fissures are known such as the Steam Boat Springs, about 

 fourteen miles from the Great Comstock Lode, that are in the 

 actual process of being filled with a deposit from heated water 

 and vapours. Veins of crystallized mineral have been found in 

 cracks in the masonry in the bottom of a furnace, either through 

 injection of the metals composing them in a molten state or by 

 sublimation, and every one with any chemical knowledge knows 

 how metallic compounds can be produced in the laboratory by 

 precipitating metals from solution, and how these maybe redissolved 

 and deposited again in other mineral forms. 



Many believe that lodes have been formed under all or most of 

 the various conditions described, and that no particular one can be 

 made to account for all the phenomena observed, and it is quite 

 likely that such has been the case to a certain, but I believe only 

 to a limited extent, and that most modes of occurrence can be 

 accounted for by the theory of lateral secretion, combining with 

 it the probability that the minerals have not in all cases been 

 deposited at the very spot at which they entered the fissures, but 

 may in some instances have been carried by circulating currents 

 for some distance before being precipitated. This will allow the 

 theory of ascending water holding metals in solution to be some- 

 times, but not necessarily always the one by which the metals or 

 mineral matter have been conveyed and lodes formed. 



As regards the auriferous lodes of Australasia and other parts 

 of the World, they certainly do not in my opinion bear any sign 

 of igneous injection, for not only does it seem impossible for such 

 a complete ramification or network of quartz veins, as commonly 

 occurs in rocks in our gold fields, to have been formed by the 

 injection of molten matter, but deposits of quartz and ore are 

 found completely separated from any other lode or vein, and show 

 no inlet through which molten matter could have found its way. 

 One would naturally also expect to see some evidence of intense 

 heat in the baking or hardening of the sides of the fissures, as 

 may be seen where sedimentary strata are in contact with igneous 

 rocks, such as dykes of dolerite or other rocks of volcanic origin, 

 which have been at one time in a highly heated state. 



The sublimation theory is also met by somewhat similar 

 difficulties, as to the way in which metals could reach such places 



