568 SUPPLEMENT. 



which extend across the others must be the most 

 Ancient and modern; the ancient having been broken by a 



modem veins. 



later subsidence of the mountain. Werner in- 

 forms us, that in the mining district of Freyberg 

 there are two kinds of veins, of very different de- 

 scriptions. One kind consists of those which are 

 called northern and southern, that is, they run 

 from nine to three hours, according to the miners' 

 compass, or between the north-west and the north- 

 east. They yield galena, black blende, pyrites, 

 either coppery, arsenical, or common; quartz, 

 and brown spar. The second kind of veins, 

 always traversing the first, and never traversed by 

 them, contains galena with a little radiated pyrites, 

 barytes, fluor, and quartz. This extends betwixt 

 the sixthuand ninth hour. One district contains 

 veins of tin and of silver, the former being always 

 traversed by the latter. The direction of the first 

 is chiefly between six and nine hours, while that of 

 the last is between nine and three. 



Accidences. In a more immediate consideration of the veins 

 themselves, it may be observed that they have 

 sometimes neither skirts nor salbands, but pass 

 into the rock itself, which in that case is often 

 somewhat decomposed. Werner says, that this 

 particularly happens when veins, loaded with 

 quartz and hornblende, occur in a quartzy gneiss ; 

 and sometimes only in particular parts, while the 



