278 MINERALOGY. 



colliery at Whitehaven is very extensive, the excavations having 

 been carried for miles beyond low-water-mark, under the bed of 

 the sea. This was the case also at Workington, where, in 1837, 

 through the criminal temerity of an agent, who persisted, though 

 warned by the old workmen, in removing the pillars of coal left 

 to support the roof of the mine — the sea broke in and filled the 

 whole of the works, destroying many lives, and property to the 

 value of £120,000. This mineral is deposited in "seams or bands" 

 varying greatly in quality and thickness — and also in depth — 

 "some cropping out" at the surface and others lying at an 

 unknown distance below it. 



Ikon. — The mineral of the district next, or perhaps equal in 

 value to coal, is Iron, the ore of which metal is found in great 

 abundance in Furness, and in West Cumberland, in the district 

 lying immediately north of Egremont, and also in more limited 

 quantity, in Millom, Eskdale, and other localities. In 1857, the 

 iron-mines in Low Furness yielded ore to the amount of 560,000 

 tons, and in the same period there were drawn from the Cumber- 

 land mines about 198,000 tons, making the yield in the whole 

 district, say, 758,000 tons. It occurs chiefly in the form of a red 

 oxide, and is deposited in masses, varying greatly in dimensions, in 

 the cavities of the limestone rock of the country. It is occasionally 

 found close to the surface, but more frequently at considerable 

 depths. Another form in which iron occurs in the district is that 

 of sulphuret, or iron pyrites. This is nowhere worked for profit 

 now, though it is widely diffused throughout the great green-slate 

 and some other formations, and large quantities exist in the waste 

 heaps of the Coniston mines. It is also found in the carboniferous 

 series, amongst the Cumberland coal measures, especially at Har- 

 rington, where it was till lately used in the manufacture of certain 

 chemicals. Iron occurs also as a magnetic oxide, and in various 

 other combinations, the most interesting of which is that known 

 by the popular name of tvad, blacklead, or plumbago. This is 

 found only in Borrowdale, and is one of the multitude of valuable 

 minerals deposited in the green-slate rock, in which it lies in 

 irregular heaps or "sops." Statistics of this mineral are not 



