630 THE LOWER SILURIAN PERIOD. 



disseminated gold than those which are deficient in visible gold. 

 Some of the richest veins indeed rarely show visible gold, while 

 others which contain nuggets are in other respects very poor. A 

 specimen of calcareous spar from the Waverley vein, given to me by 

 the superintendent, seemed to be of later formation than the quartz, 

 and to have filled a "vug" or cavity; but in a specimen from the 

 Britannia Mine, presented to me by Mr R. G. Fraser of Halifax, 

 a magnesian and ferruginous calc-spar holding gold occurs near the 

 wall of the vein, and is interlaced with thin veinlets of quartz which 

 are highly auriferous. Gold also occurs occasionally in the slate 

 forming the wall of the vein, occupying minute crevices in the rock, 

 and I observed at the Montagu Mine, near the "Waverley, that gold 

 occurs in thin veins of quartz and mispeckel, penetrating the slate 

 to some distance from the main vein. At the Montagu Mine the 

 vein worked is from four to eight inches thick, and is enclosed in 

 gray slate nearly vertical, and with strike "W. 5° S. to W. 10° S. 

 Another smaller vein occurs at a distance of fifteen feet ; and about 

 five feet from this last the slate gives place to quartzite, which in 

 this vicinity appears to alternate frequently with the slate. 



No geologist who examines these veins can, I think, doubt their 

 aqueous origin ; but different opinions may be entertained as to the pre- 

 cise mode of introduction of the metallic minerals. The facts already 

 stated, in reference to the structure and mode of occurrence of the 

 veins, and the manner in which the gold is associated with the other min- 

 erals present, appear to me to prove conclusively that the veins were 

 formed at the time of the disturbance and alteration of the containing 

 beds, and in consequence of the mechanical and chemical changes 

 then in progress. In this case the gold and other metallic minerals 

 were probably contained in a state of solution in alkaline sulphurets, 

 in the silica-bearing heated waters which penetrated the whole of the 

 beds, and from which, as from a sponge, these silicious and metallic mat- 

 ters have been pressed out in the folding and contortion of the beds. In 

 Nova Scotia it appears that those changes by which the older sedi- 

 ments have been brought into their present state occurred in the latter 

 part of the Devonian period, as I have pointed out in my paper on 

 these rocks in the "Canadian Naturalist and Geologist" already 

 referred to, and in a previous chapter of this work. Accordingly, in 

 one of the gold districts of Nova Scotia, as already explained,* nuggets 

 and grains of gold are found in the Lower Carboniferous conglomerate 

 associated with debris of the qnartzose and slaty matrix. This inter- 

 esting example, first noticed by Mr Hartt, proves that the gold veins 

 * See above, under " Carboniferous," p. 277, ante. 



