Mr. William Phillips on the Veins of Cornwall, 127 



promising iron pyrites, which occasions its being abandoned ; in 

 others are found the ores of tin or copper, sometimes both, inter- 

 mingled with some, or even most of the foregoing substances j 

 but if they occur together, the copper for the most part prevails to 

 such an amount, as that all traces of tin are lost in depth. In some 

 veins however they continue to be found, even to a considerable 

 depth, though not often much intermingled but in separate bunches; 

 this as has already been noted, was the case in Cook's Kitchen Mine; 

 the neighbouring mine. Tin Croft, also furnished a somewhat similar 

 instance, though not I believe in the same vein ; but these must be 

 considered as somewhat rare occurrences. 



Tin is commonly found much nearer the surface than copper. 

 When either is very near, especially if abundance, it is in the esti- 

 mation of the miner an indication that it will not continue to a very- 

 considerable depth, of which Cornwall furnishes numerous instances. 

 There is a tract of country situate about midway between Truro 

 and Redruth on the north of the high road, in most of the mines of 

 which, and amongst them the great mine called North Downs, the 

 ore for the most part occurred near the surface, and was almost 

 uniformly found to extend but to a small comparative depth. 



Although there are veins in various parts of the country which 

 have yielded copper in its pure state in considerable abundance, in 

 masses interspersed through them, and but little intermingled with 

 other substances, or even with the ores of copper, yet the most com- 

 mon state in which this metal is found is that called yellow copper 

 ore. It is more continuous and lasting than any other. There are 

 veins which yield only the grey sulphuret, but this rarely or never 

 continues, being found only in bunches. It is sometimes mingled with 

 the yellow ore. As a proof of the great difference in the value of 

 the ores of veins, it may be noticed that there are many which 



