Ill 



In and around the Caldbeck Fells this ore has undergone a 

 good deal of decomposition where it occurs near the surface, and 

 its constituents have entered into numerous fresh combinations. 

 In 1880 no copper was returned as having been raised in Cumber- 

 land and Westmorland, although in former years it was one of the 

 most important ores of the district. 



The well-known Iron Pyrites, Mundic, Sulphur Ore, or Iron 

 Bisulphide, occurs in tolerable abundance in nearly all the mines 

 throughout our district, whatever the ore may be that the veins are 

 especially worked for. Hence the mineral is tolerably familiar to 

 nearly all. Very beautiful cubical crystals of Pyrites occur in some 

 of the mines near Keswick, and are in great request for ornamental 

 purposes. At one time some pyrites was systematically worked 

 in the Alston district for the manufacture of Sulphuric Acid ; but 

 the demand for this purpose is now more generally met by supplies 

 from foreign sources, especially from Spain and Portugal. But 

 even yet five hundred tons, worth about ;^25o, were raised in 

 Cumberland in 1880. 



The general distribution of Iron Sulphide in veins may really be 

 due to the circulation and the downward flow of water from the 

 surface, which would have the effect of constantly removing the 

 products of decomposition in solution and redepositing them 

 at lower levels where suitable conditions for their reduction 

 obtained. 



Pyrites itself crystallizes in forms belonging to the Cubic System; 

 but we have another species of the same compound, called Marca- 

 siTE, or White Pyrites, that assumes crystalline forms belonging to 

 the Rhombic System. It is rather rare with us, and I have not been 

 able to discover any locality for it besides that of the mines in the 

 Alston district. At Garrigill Mine it occurs crystallized upon 

 Calcite, and there is a specimen of this mineral in the British 

 Museum, from Snappergill Mines, which consists of an irregular 

 aggregation of rhombic crystals with pointed ends, shaped some- 

 thing like the knives of a mowing machine, and which has the 

 entire surface of the mineral tarnished, as usual, to nearly black. 



