Geology of Northumlerland. 265 



the fact is, tliat so far from this being a rare occurrence, it is 

 almost a genera! law, at least in England, where I believe mimmr 

 operations have been carried on to a far greatfr extent, and 

 wil/i more capital and skill, than in any part vf Germany. 



" The principal substances which yZ// the veins in this mineral 

 district, besides galena o\ the sulplmret of lead, and idend or 



sulphurei of zinc, are quartz, fluor spar, calcareous spar " 



The author goes on describing what is called crai/sne by mi- 

 neralogists, of which the metalliferous part which is here galena 

 and blend, though the object of miners, constitutes a very minute 

 part. I might say only that the author attacks M. Werner's 

 system v.'ithout being sufficiently acquainted with it ; but as this 

 is an important point, not only m mineralogy but in geology, I 

 shall enter into some particulars. 



In the first volume of my Geological Travels in some Parts of 

 France, Switzerland and Germany, I relate a journey which I 

 made in the mountains of Freyberg with M. Werner himself. 

 We had both happened to express in the same Freiich journal, 

 the opinion, that metallic veins were fissures in the strata, while 

 still under the water of the sea ; which fssures had been filled 

 by deposits on their sides from the same liquid ; a proof of which 

 operation is, that the same. deposits are found on both sides, 

 forming what is called gangue, not necessarily metalliferous ; 

 but that some of the gangues, or part of a gangue, contained 

 ingredients wiiich, by smelting, produced 7«e;a/>- of different sorts 

 according to the veins. 



The inaccuracy of the author in stating M. Werner's system, 

 consists in ascribing to him the itlea that veins are openjissutes 

 filled with v2etallic solulions from above.; wliile he expressly 

 considers tiie filling up of the veins as a progressive operation, 

 by successive deposits from the liquid of the sea against the sides 

 of the fissures ; a proof of which operation is, that the deposits 

 are symmetrically formed on both sides oi the fissure. 



I had ijeen in that respect, some years before, in a very good 

 school and under a very able master. The scene was the liiineral 

 country of the Hartx, where, contrary to the opinion of the 

 author, the mining operations had heeu carried on to a much 

 greater extent than in England, not only for the extent of the 

 veins, but for the breadth and the depth in which tiiey have 

 been followed throughout their ramifications. In short, the 

 Hcirtz is one of the most celebrated n)ineral countries in which 

 veins have been worked for many centuries; and surely the 

 author was not acquainted with it, when he thought tkat in no 

 part of Germany the mining operations had been carried so far 

 as in Englujid. 



My guide in that great miueral scene was my late intimate 



friend 



