190 



It is probable that small additional layers of quartz 

 and some gold may have been added to the gold-bearing 

 leads, during and after the granite intrusion but, so far 

 as known, this has not been proved by observation in 

 the field. 



Little study has been given to the cause of the precipita- 

 tion of the metallic contents of the veins. The ascending 

 thermal solutions were no doubt subjected to different 

 chemical and physical conditions, but it is difficult to 

 surmise what these were and what has been their effect. 

 Some factors that may have entered in the problem are, 

 (i) decrease of pressure that the solutions underwent on 

 entering the fissure, (2) lowering of temperature, (3) effect 

 of other solutions originating from below or from the earth's 

 surface, and (4) effect of certain solid contents in the rocks. 

 Certain slates apparently exercised a greater precipitating 

 effect than others. These are generally black and are fre- 

 quently impregnated with arsenopyrite, pyrite or pyrrho- 

 tite, and the interstratified veins that can be worked 

 with profit are usually found in beds of this character. 

 In some cases the cross veins also are found to be enriched 

 where they lie in contact with strata of this class. 



The question of secondary enrichment has received 

 little study and little is known with regard to what extent 

 the fracture zones of the districts have afforded means for 

 the passage of meteoric waters and a secondary redistribu- 

 tion of the mineral contents of the veins. 



Briefly stated, the observed facts seem to be best explained 

 on the theory that the veins are epigenetic, that they were 

 formed by the deposition of quartz, sulphides and gold 

 in cross fractures and interbedded openings occurring 

 chiefly in the black or pyritous slate beds of the Golden- 

 ville formation, that the conditons necessary for the 

 formation of the veins were a great deal of fracturing across 

 the bedding planes, permitting the passage of ascending 

 thermal solutions and that these fractures were produced 

 where the two horizontal orogenic forces manifested them- 

 selves in the formation of domes or the pitching of the 

 anticlines. 



PRODUCTION. 



Gold was discovered in Nova Scotia in i860, and mining 

 operations then commenced. Two years after the dis- 

 covery, gold valued at nearly $142,000 was recovered from 



