METALLIFEROUS DEPOSITS. 58 1 



Somersetshire, in Cornwall, and in the Carboniferous rocks at Weardale in Durham, 

 etc. Magnetic iron-ore occurs near Hey Tor in Devonshire. Red and brown 

 oxides of iron have been worked in the Carboniferous rocks, etc., of the Furness 

 District, etc. (see pp. 83, 163), Northumberland, Llantrissant in Glamorganshire, 

 Bristol, and in the Forest of Dean ; in the Devonian rocks of Restormel 

 (where fine specimens of Gothite have been obtained), and other places in 

 Cornwall. 



Iron-ores (chiefly brown ores) have been obtained from the Lower Greensand of 

 Seend in Wiltshire, and Tealby in Lincolnshire ; from the Wealden Beds of 

 Sussex and Kent (clay-ironstone) ; the Corallian Beds of Abbotsbury in Dorset, 

 and Westbury in Wiltshire ; from the Northampton Sand of Wellingborough, 

 etc. ; and from the Dogger of Rosedale in Yorkshire (magnetic iron-ore) ; from 

 the Middle Lias of Fawler, etc., in Oxfordshire, Grantham and other places 

 in Lincolnshire and Leicestershire, and the Cleveland district in Yorkshire 

 (carbonate of iron, etc.) ; the Lower Lias of Scunthorpe, etc., in Lincolnshire; 

 and from the Triassic rocks of Somerset, etc. 



Pyrites, iron-pyrites (bisulphide), occurs in most strata ; it is not available as a 

 metallic ore, but is used in the preparation of sulphate of iron and sulphuric acid, 

 hence it is sometimes known as 'sulphur-ore.' In Cornwall the name 'mundic' 

 is applied to various forms of pyrites, although it should properly be restricted 

 to arsenical pyrites. Marcasite is a species which crystallizes in prismatic or 

 rhombic forms, some of which are known as 'Cockscomb pyrites' : fine examples 

 occur at Folkestone. 



Iron, as employed in the arts, for the manufacture of 'hardware,' etc., contains 

 carbon in variable proportion. Cast-iron, or pig-metal, is hard and comparatively 

 brittle, and contains from 2 to 6 per cent, of carbon ; wrought or malleable iron 

 is nearest to the pure metal, and contains little or no carbon ; while steel contains 

 an amount of carbon intermediate between that in wrought and cast iron.^ 



Both red and brown oxides of iron are used in the preparation of pigments ; 

 and hrematite, when reduced to powder, is used for polishing. (See pp. 220, 232.) 



Lead Ores, 



Native lead is of rare occurrence, but it has been found at Alston Moor, and 

 some other localities. Galena (sulphide) is the more important ore ; the purer 

 varieties contain upwards of 86 per cent, of the metal, but silver is usually present, 

 and is extensively extracted. Cerussite (carbonate) is largely used for white paint 

 (as an artificial preparation), and is known as white-lead-ore. Minium (red oxide) 

 is of the same composition as 'red lead,' but the latter is always prepared 

 artificially. Among other lead-ores there are anglesite (sulphate) and pyromorphite 

 (phosphate). Lead-mining has been carried on in this country since early British 

 and Roman times. 



In Cornwall and Devon the lead-ores occur in the Devonian ' clay-slate ' in 

 regular veins or lodes, mostly in the cross-courses running north and south. There 

 are lead-mines at Menheniot and Herodsfoot, near Liskeard, in Cornwall, and at 

 Beer Alston and Combe Martin in Devon. 



There are lead-mines in the Cambrian rocks of Cardiganshire, Merionethshire, 

 Montgomeryshire, and Shropshire, and in the Carboniferous rocks of Denbighshire 

 and Minera in Flintshire. In the Isle of Man the mines of Foxdale and Laxey are 

 situated near the junction of slates and granite. In Northumberland, Durham, 

 Westmoreland, Cumberland, Yorkshire, and Derbyshire, much lead-ore has been 

 obtained from the Carboniferous rocks. The East and West Allendale and 

 Derwent mines, and those of Weardale, Teesdale, and Alston Moor are the more 

 important sources. From the 'lead-measures' of Alston Moor in Cumberland 

 upwards of 4000 tons have been obtained in one year.- (See pp. 163, 167.) 



' Bauerman, Treatise on the Metallurgy of Iron, ed. 5, 1882. 

 - T. Sopwith, P. Geol. Assoc, i. 314 ; J. Morris, G. Mag. 1869, p. 317 ; De 

 Ranee, Ibid, 1873, pp. 64, 303 ; Goodchild, Trans. Cumb. Assoc, vii. 107. 



