of Devonshire a?id Cornwall. 171 



The relative age of the different formations of silver, according to 

 Werner, is not yet determined.* The vein which was formerly 

 worked at Huel Mexico in Cornwall, was in grauwacke slate. The 

 ore appeared to be mixed in it in the form of insulated masses or 

 nests ; besides the native silver, corneous ore (muriate of silver) was 

 also met with. This last ore, of all the combinations of silver, is that 

 which is most frequently found at the surface of veins.f 



Silver united with lead in the state of galena is found in the mine 

 of Huel Pool, and filiform native silver, with vitreous silver and 

 decomposed galena, has been met with at Herland ; we know that 

 these two metals combine very readily, so much so, that we rarely 

 find a mine of lead which does not contain more or less silver. The 

 mines of Beer-alston in Devonshire, contain a pretty large propor- 

 tion of it. The most important mineral deposit at Freyberg is of 

 silver and lead. 



Grey antimony ore (sulphuret) is sometimes found in primitive^ 

 and sometimes in secondary mountains. According to most geolo- 

 gists it belongs to the middle ages of our globe. It was formerly 

 worked in different parts of Cornwall ; among others at Padstow 

 Harbour and Camelford near St. Teath, and more lately at Huel 



Bismuth unaccompanied by any other metal does not form veins, but kidney-form 

 masses. Thomson's System of Chemistry. 



I do not know exactly under what form the bismuth has been found at Dolcoath, I 

 "believe in the kidney form. 



* At Freyberg and in Norway, silver is found in gneiss, at Johanngeorgenstadt in 

 clay slate, mica slate and hornblende, Nouvelle Theoric de la formation des filons. 



According to Bergman, silver is found in quartz, limestone, and sometimes in petro- 

 silex. It is often accompanied with blende, pyrites of different metals, among which 

 may be particularly noticed, antimony, zinc, cobalt and lead. Journal des Mines, 

 No. xvi. p. 25. 



+ At Frankenberg in Hesse, leaves of native silver have been found upon petrifaction*. 

 Nouvelle Theoriede la formation des filons, p. 185. 



y 2 



