130 The Alder ley Copper-mines. 



embedded in the "Bunter Sandstein," lie the Alderley 

 copper-mines. ' Until latterly these mines were little 

 more than a myth, but now they are worked to a profit. 

 The chief of them had the character, at first, of an open 

 quarry. Shortly afterwards it was extended by driving 

 tunnels into the rock, two of them towards the north-west, 

 and one to the south-east, and of the former, one has 

 now acquired the proportions of an immense cavern. 

 The width of the opening is about fifty feet, the height 

 varies from forty to sixty feet, and to the extremity the 

 distance is two or three hundred yards. Of course, it is 

 only when lighted up artificially that, as in the case of 

 the Northwich salt-mines, a correct idea can be formed 

 of the extent of the cavern. This was done, as at North- 

 wich, on the occasion of the visit of the British Associa- 

 tion, September 1861, and then the immensity of the ex- 

 cavations became apparent. Running parallel with the 

 deposits of copper there is also found lead. The ores of 

 the former metal consist of a perpetually varying mixture 

 of arseniate, carbonate, oxide, and phosphate of copper, 

 the arseniate predominating. These substances are 

 diffused throughout a whitish sandstone, in which is 

 often contained also a considerable quantity of sulphate 

 of barytes. Cobalt is likewise met with here. The quan- 

 tity of copper is extremely variable, some of the sand- 

 stone being densely impregnated, and beautifully green, 

 while other portions possess scarcely an atom. The 

 poorer condition prevails, so that the average proportion 



