Metalliferous Veins. 155 



which extend in various directions. And, lastly, a parallel 

 series of veins frequently meets a cross vein, either on the line 

 of its course or of its depth ; some of these veins continue their 

 direction on either side of the cross-vein, whilst others on the 

 opposite side of the cross-vein abruptly disappear, on the line 

 of their original course, and are often found at some distance 

 therefrom, but running in a parallel direction. 



" On a small scale, as in the granite of Carclaze, arid in the 

 slate of St Agnes, these branched and intersected veins are 

 beautifully illustrated, parallel ramifications may be seen de- 

 parting from either side of the veins, and in the case of inter- 

 sected veins they sometimes preserve the same course on both 

 sides of the cross-vein, but often exhibit the peculiar arrange- 

 ment called by the miner a heave. 



" Veins vary very much in their composition ; in general 

 they consist entirely of earthy minerals, which, indeed, even 

 when the veins are metalliferous, constitute the greater part 

 thereof, the ores seldom being continuous for any considerable 

 distance, but being scattered and disseminated throughout the 

 matrix in short irregular veins, layers, bunches, granules, crys- 

 tals, and smaller forms ; sometimes, indeed, but rarely, except 

 in very small veins, the ore entirely prevails." 



The prevalent idea of Cornish lodes is, I believe, rather im- 

 perfect, and those who suppose veins to have regular walls, and 

 to have been derived from fissures, would not recognise as such 

 layers of schorl-rock, of porphyry, of hornstone, and even of 

 granite itself; but these are called lodes by the miners (Mr 

 Carne states, that in Huel Unity, the elvan is so rich in tin, 

 that it is considered as the tin lode) when they abound in me- 

 tallic minerals. Even the most regular tin and copper lodes 

 are very complex in their composition, quartz generally pre- 

 vails in their matrix, but is always more or less blended or 

 mixed with a substance similar to the adjoining rock ; indeed, 

 the latter often occurs in distinct forms, as nodules, angular 

 pieces, and even masses of considerable size, which are inde- 

 pendent of the main rock, being completely enveloped in the 

 quartzose part of the lode. These are of such common occur- 

 rence as to have been named by the miners horses of killas. 

 Sometimes the schist so abounds in the lode that the quartzose 



