150 OEIGIN AND DEVELOPMENT OF OBE-DEPOSITS. 



sunk below the 60 where good yellow copper ore made its 

 appearance ; but discouraged by the low prevailing prices, the 

 water being "very quick" was let in, and work was for the 

 time confined to the adit level, and subsequently to sinking in 

 other places where there was not much water to contend with. 

 The lode was said to be " 240-feet wide."*' It was undoubtedly 

 very wide as I can testify, but this great apparent width was no 

 doubt due to its lying very " flat " in that part. 



At Duchy Peru, just east of Great Eetallack, the " old 

 workings " have been carried to a depth of 50 fathoms on the 

 N.S. lead-copper lode — the " Peru lode," celebrated for the 

 richness of the silver specimens it has yielded.f The workings 

 on the iron lode before the mines were re-opened:]: about 1871, 

 had been carried down between 20 and 30 fathoms, and this 

 depth was increased to 40 fathoms b}' March, 1873. 



Roebuck's shaft is vertical, 12-ft. by 7-ft., fitted with ladder- 

 ways and containing a column of 18" pumps. § By the year 

 1881, it had been carried down to the 70 fathom level; since 

 then, I believe, no further sinking has been done, and at the 

 present time not only Duchy Peru but practically all the mines 

 on the great lode are idle. 



The killas country about the great lode at Duchy Peru 

 seems to be much disturbed. South of the lode it is hard and 

 appears to dip towards it, but near the lode it is soft and dips 

 with it, as shewn in the sketch (fig. 9, Plate viii), just as is common 

 in the case of faults in yielding strata. Eastward from Duchy 

 Peru is Deerpark mine, from which considerable quantities of iron 



*Ibid. 



fit was only a few incLes wide, but it yielded silver-lead of great ricliness, 

 some parcels containing as much as 2000 ounces to the ton of ore, a part of the 

 silver being '' native." 



JBy the Cornish Consolidated Iron Mines Corporation. 



§The condition of the mine in the middle of 1873 was described in detail in 

 the paper by the present writer already referred to, as also the condition of the 

 remarkable hot "end" at the 20 fathom level east of Vallance's shaft. The 

 temperature in October, 1873, was 124° F., at surface 64° F. This high temper- 

 ature was attributed to the oxidation of pyrites — and the same cause was in 1881 

 assigned for the high temperature in the 60 fathom cross-cut north — which 

 however was only 82° F. against a surface temperature of 52° on the 26th October, 

 1881- 



