144 ORIGIN AND DEVELOPMENT OF ORE-DEPOSITS. 



The other mines on this great lode now reached depths as 

 follows : — Cook's Kitchen, 400 fathoms ; Tincroft, 300 fathoms ; 

 Carn Brea, 312* fathoms. 



The mining cost which includes cost of management, water 

 charges (pumping), winding, dead- work, development, supplies, 

 new erections and wear and tear, amounts to about 15/6 per 

 ton, the dressing cost is about 4/-, or together about 19/6. 

 The actual cost of breaking the ore in 1870 was, in Dolcoath 

 6/6 per ton, which sum included winding and tramming. The 

 cost of driving a level 6 feet wide and 8 feet high was £20 per 

 fathom. 



The production of the four mines for the 10 years from 

 1872-81 was 32,430 tons of tin ore, 6,692 of copper ore (nearly- 

 all of this from Carn Brea Mine), and 1,901 tons of arsenic. This 

 production has been largely increased during the succeeding 

 decade, Carn Brea having especially improved. In 1890 the 

 produce of tin ore was as follows : 



Dolcoath . . . . 2023 tons. 



Cook's Kitchen .. 206 ,, 



Tincroft .. .. 894 ,, 



Carn Brea . . . . 1671 ,, 



Total 4794 „ 

 or considerably over y^ths of the total production of the West of 

 England, f 



The total value of the produce of Dolcoath Mine alone has 

 probably been not less than ten millions sterling, the details of 

 the estimates being as follows : 



* The following particulars of the working cost on these four mines as given 

 by Mr. E. J. Frecheville {Trans. Boy. Geol. Soc. Corn., x, 146, 1882) will be 

 read with interest. There is probably but little difference since the date of the 

 paper except that the yield at Carn Brea has greatly improved. 



1872-81. Average yield. Mining cost. Dressing cost. Total cost. 



lbs. per ton. 

 Dolcoath ... 59 

 Cook's Kitchen 43 

 Tincroft ... 53 

 Carn Brea ... 35 



per ton. 

 16 11 ... 3 101 ... 1 9i 

 16 4| ... 4 5i ... 1 10 



13 9 .,. 4 8 ... 18 5 



14 3 ... 3 9 ... 18 

 +The " calls " from the three eastern mines — no calls having been made at 



Dolcoath — amounted to ^856,950 during the period 1872-81, the produce of the 

 four mines realized about .£1,750,000, and the dividends amounted to ^277,226. 

 From 1882 to 1891 the dividends have been nearly ,£400,000 and the calls less 

 than .£100,000, Dolcoath having made no call during the entire period . 



