126 Mr. William Phillips on the Feins of Cornwall. 



few fathoms below the surface, it assumes more determinate marks 

 of being a iissure. 



Contents of East and West or Metalliferous Veins, 



The contents or load of the generality of veins, if at all attached to 

 their sides, are for the most part easily separated* A dark ochreous 

 crust occasionally covers one or both sides of the vein, technically 

 called the walls of the load; and when these, or at least one of them, 

 is regular and determinable, they are more encouraging to the 

 miner than when rough and uneven. A thin coating of flucan Is 

 found on one, or occasionally on the other wall, or sometimes on 

 both walls of a metalliferous vein, as described by pi. 6. fig. 4. but it 

 is said that this coating or vein of flucan is most commonly found 

 on that which, in regard to the underlie of the vein, may be called 

 the upper wall. 



It has been already noticed, in speaking of the denominations 

 of metalliferous veins, that there is a great diversity in their loads 

 or contents, and that the same vein exhibits so little uniformity in 

 that respect, at different depths, as to assume various characters. 

 Near the surface the load consists for the most part of a sort of 

 ochreous rubble, probably the debris of the neighbouring country ; 

 beneath which, though rarely nearer grass than 20 or 30 fathoms, 

 are found some metalliferous indications. These, If gossan be the 

 prevailing substance, consist of the ores of tin or copper. But iron 

 pyrites, blende, fluate of lime, quartz, and sometimes chlorite, or 

 flucan, frequently prevail for many fathoms, occasionally mixed 

 with portions of the country through which the vein passes, though 

 frequently with but slight traces either of tin or copper. A vein is 

 sometimes found to consist of little else than a bed of hard and un- 



