444 Transactions. 



or other agency before or during ejection ; (2) action of the 

 magma on the first-formed crystals after it had attained its 

 present position ; (3) subsequent action either of percolating 

 water from above or below, or of water which constituted a part 

 of th3 magma at a high temperature and charged with sulphur 

 or sulphides. 



The first of these is out of the question, since the movement 

 of the mass during ejection would have detached and scattered 

 throughout the mass the granular particles surrounding the 

 hornblende core. It is certain that the presence of the pyrites 

 in large masses in the rock is closely connected with its pre- 

 sence in small granular masses in the resorption zones, and 

 therefore the formation of the zones was contemporaneous with 

 the introduction of the precious metals. Taking it as probable 

 that the mass was ejected after the outflow of the bostonite, 

 we have two facts which have bearing on tne matter : one the 

 presence of a small zone of pyrites bearing syenite, the other the 

 total absence of pyrites and gold and silver from the micaceous 

 sandstone. The enrichment of the syenite and bostonite by 

 ordinary vadose circulation is not probable, firstly on account 

 of the absence of any possible gold-bearing bodies except the 

 deeply buried schist, and secondly on account of the limited 

 enrichment of the bostonite, a rock quite as porous as the syenite. 

 There is absolutely no reason why the enrichment of this should 

 have ceased a few inches from the junction of the rocks. The 

 subsequent penetration of the mass by highly heated and sul- 

 phide-charged water from below, if this penetration occurred 

 after the consolidation of the syenite, is for the same reason 

 untenable. 



It is thus to the magma or to some portion of the magma 

 itself that we must look as the mineralising agent. Since the 

 syenite has only been assayed in samples taken from the sur- 

 face, it is impossible to say whether the rock may or may not 

 be gold-bearing throughout its mass, and this leaves the solu- 

 tion of the problem to theoretical reasoning. However, we 

 have seen tha^ in all probability the reaction did not occur in 

 the magma before ejection, and can conclude that the particular 

 constituents which finally caused this action were not then 

 concentrated enough to bring this about. When, however, the 

 magma was forced up nearer the surface the mass would com- 

 mence to solidify, and the portions of it which remained liquid 

 longest would rise to the place of least pressure — that is, the por- 

 tion nearest the surface. They would do this without diffi- 

 culty in the semi-solidified viscous mass. At the surface they 

 were, however, retained by the solid bostonite, which, however, 

 they penetrated for a few inches, and the action causing the 



