170 Dr. Berge-r o;; the physical Structure 



stances that have been found to accompany the veins are, arsenlate 

 of iron in the mines of Carrarack and Huel Gorland, oxide of 

 uranium in the state of ochre, in Tin Croft mine ; bismuth and 

 nickel at Dolcoath, spathose iron at Cook's-Kitchen, and native silver 

 united w^ith decomposed galena in the mine of copper and silver at 

 Herland. Judging of this formation of copper from its being ac- 

 companied by bismuth and uranium, v^'^e should be led to consider it 

 as very old. Uranium and bismuth being found in this district 

 proves, that those metals may, contrary to the opinion of Werner, be 

 met with in secondary mountains. The nickel, cobalt,* silver, and 

 especially the spathose iron, would lead us on the contrary to refer 

 that formation to a much more recent epoch,'!' insomuch, that we 

 must perhaps admit, that in the deposits of copper in Cornwall, 

 there are veins of different ages. 



It may be possible also, and this idea seems to me the most pro- 

 bable, that the accompanying substances which contradict the uni- 

 formity of age in veins of copper, are met with in rents formed at 

 a later period, or in the veins called cross-courses^ of a still more 

 recent date.:): It is only however from practical miners, that we can 

 hope to obtain information on this head. 



'* Native copper is found in very considerable quantity at Cape Lizard, between the 

 " rocks near the sea shore, in filiform branches, and veins of some <hickness, contained 

 " in blackish serpentine, in Huel Virgin, Carrarach, at Poldory in the clefts of moun- 

 " tains composed of killas." Klaproth's Miner. Qbserv. 



* " At Huel Trugo also, a copper mine near St. Columb, some of the purest Cobalt 

 " has been worked. Very good cobalt has been also discovered in Dudnan's mine in 

 " lUogan parish." Pryce's Miner. Cornub. 



+ Ramond has also found in the Pyrenees indications of nickel and cobalt, at the 

 junction of the veined granites with the corneenneSy i. e. in a geological situation very 

 analogous to that of Cornwall. Voyages au Mont Perdu, p. 206 and 239. 



J It is said, however, that bismuth never accompanies cobalt and nickel in deposits of 

 new formation. Journal des Mines, No. iviii. p. 94. 



