132 Mr, William Phillips c>/ the Veins of Cornwall,' 



occurred ; and I was informed by Capt. William Davey, of Redruth, 

 one of the most skilful and intelligent practical miners of the present 

 day, and who was the principal manager of Huel Gorland mine, that 

 for some fathoms both in length and depth one wall of one of its 

 veins was of granite and the other of schist ; another instance is men- 

 tioned in the annexed notice of the accompanying section of Tin 

 Croft mine. 



The alterations in the country from schist to granite and back 

 again to schist, are very frequent in some of the mining districts of 

 Cornwall, so that it is impossible in a word to say in which some of 

 the mines are situated, but I suspect this to be principally the case with 

 those mines that are at the foot, or in the immediate neighbourhood 

 of granite hills. I have not noticed any instances of the junction of 

 these two substances in which the granite has not shewn a tendency 

 to decomposition : it is sometimes separated from tlae schist by a 

 slight ferruginous seam, 



it will of course be understood that great variations in the texture 

 and hardness both of granite and schist are observable. Of the for- 

 mer there seems every possible difference in hardness between the 

 decomposed granite of Tol Cam mine, which, as well as that of several 

 others, it was impossible to keep apart without lining the adit or 

 the level with boards close to each other, both above and on each 

 side, and the compact and fine grained granite, of which quartz forms 

 a principal ingredient, and which in hardness is almost equal to por* 

 phyry. Of the great difference in the hardness of schist, I shaU 

 notice one instance in Huel Alfred ; in the sinking of two shafts in 

 that mine, not much exceeding the distance of 50 fathoms from each 

 other, the pay to the miner was in one instance £55 per fathom, but 

 in the other only £5. 



These frequent variations in the country through which the miner 



