270 PROCEEDINGS OF SECTION .C. 



even when the rock has decomposed to clay. It is oneof the last 

 minerals to decompose, but that it does dissolve slowly is proved 

 by the presence of iron sulphate in all the old drives. Mr. Cox's 

 theory, however, implies that all the gold and most of the gangue 

 came up from below, and I cannot accept it for the reasons 

 already given. 



Sir James Hector's theory seems to me to be more probable, 

 provided that the quartz be supposed to come from the bed-rock 

 equally with the gold ; but it does not satisfy me altogether 

 because — (1 ) I cannot see how, during any stage of alteration of the 

 rocks, auriferous pyrites could be removed from the i"ock, and, in 

 the absence of organic matter, be redeposited as auriferous pyrites 

 in a fissure in the neighbourhood ; (2) pyrites is not confined to 

 the volcanic series, but occurs also in the slate formation, but gold 

 does not accompany it there ; and (3)1 rather doubt the state- 

 ment of the intimate relation between pyrites and gold. 



It is certainly by no means the case that gold occurs wherever 

 pyrites is abundant, or where it has once been abundant. The 

 rocks contain quite as much pyrites in the Karaka and Tararu 

 Creeks as they do in the Moanataiari and Waiotahi Creeks, but 

 the gold is much less in quantity in the former localities than in 

 the latter ; indeed the two rocks described in this paper from the 

 Prince Imperial and Waiotahi Mines contain very little pyrites, 

 although one of them encloses a very rich vein, and there is no 

 evidence to shew that they even contained more than they do now. 

 The rocks of Te Aroha and of Heevin's Point at Coromandel also 

 have much pyrites, but not much gold ; while the slates and 

 felsite tufi* at Waiohanga Point are largely impregnated with 

 pyrites, and yet there is no gold, although in places the pyrites has 

 been completely decomposed. On the other hand, the rocks of the 

 lower part of the Shellback Creek contain little or no pyrites, and 

 little or no gold. 



Again, I am not convinced that the pyrites of the country rock 

 is so uniformly auriferous as is generally supposed. That the 

 pyrites from the lodes is auriferous I allow, but the evidence that 

 the pyi'ites of the country rock is also auriferous is but slight. 

 In 1868 Dr. Hector exhibited, at a meeting of the Auckland 

 Institute, pyritous vein rock from the Golden Crown, which was 

 highly auriferous, and a portion of the bed-rock which also 

 contained gold, but it is not stated that in the latter case the gold 

 was in pyrites. In 1869 Dr. Hector, speaking of pyritiferous 

 rock from the Kapanga Mine, Coromandel, says, " It was from 

 this rock that the iron pyrites formerly examined for gold was 

 obtained, which yielded at the rate of 4 oz. to the ton." But on 

 turning to these analyses I find that the pyrites is said to have 

 been brought from an auriferous leader, and from the Kapanga 

 Mine ; it is not said to have come froni the country rock. Mr. 

 AV. Skey says that in two cases at the Thames, pyrites was i*oughly 



