270 MINES 



Morbihan, where a quartzose tin-bearing vein intersects the granite, in the direction 

 E.N.E. and W.S.W., and centains also mispickel, topaz, and beryl. These localities 

 have afforded very fine specimens of tin ore, excellent examples of which appeared at 

 the Paris Exposition in 1855; but although frequent trials have been made upon 

 them, they have not yet led to an extensive and systematic working. 



The most important exploitations in this district are the lead mines of Pouttaouen 

 and Hurlgoat, situated near Carhaix. The mine of Huelgoat, celebrated for the plomb- 

 gomme (hydro-aluminate of lead) discovered in it, is opened on a vein of galena, which 

 traverses clay-slate rocks. The workings have subsisted for about three centuries, 

 and have attained to a depth of 270 meters. 



The lode has been followed over a horizontal distance of about 1,000 meters, and 

 contains, besides argentiferous galena, ochreous substances yielding about yooc>th f 

 silver in the native state, or as chloride. 



The vein of Poullaouen, called the New Mine, was discovered in 1741. It was 

 powerful and very rich near the surface ; but it became subdivided and impoverished 

 with its depth, notwithstanding which the workings havp been sunk to upwards of 

 250 meters below the surface. In these mines there are fine hydraulic machines for 

 the drainage of the waters, with wheels from 14 to 15 yards in diameter; and water- 

 pressure machines have been some years since constructed there. 



The vein courses through groywacke in a direction N. 22 E., and, including five 

 branches, has in some placec reached the width of 60 feet. 



The annual produce of these mines is 300 tons of lead and 1,400 kilograms of silver. 

 Several veins of galena exist at Ckdtelaudren, near Saint-Brieuc, but they are not 

 worked at present. There is also one at Pontp&in, near Rennes, which has been 

 worked to a depth of 140 yards, but has in like manner been abandoned. It affords, 

 besides the galena, a very large quantity of blende (siilphuret of zinc), considerable 

 amounts of which, cf a very crystalline character, have, during the last few years, 

 been exported. This is also a N.S. lode. 



There occurs, moreover, a lead mine at Pierreville, department of the Channel, 

 opened on a vein which traverses limestone. The same department presents a de- 

 posit of sulphuret of mercury at Me"nildot. A mine of antimony was worked at 

 La Eame'e, department of La Vendee. 



At Melles (Deux Sevres), ancient works on argentiferous galena are traceable, of 

 which the date is unknown. 



It is, however, evident that these metals are only in part the production of the 

 mines of France proper. 



MINES OF GrREAT BBITA1N AND IBELAND. 



The mines comprehended in this section are situated, 1. in Cornwall, Devonshire, 

 and Somersetshire ; 2. in the S.E. of Ireland ; 3. in the island of Anglesey and the 

 adjoining part of Wales ; 4. in Cumberland, Westmoreland, the north of Lancashire, 

 Yorkshire and Derbyshire, Durham and Northumberland, and the Isle of Man ; 5. in 

 the south and west of Scotland. 



It will be observed that the metalliferous rocks, analogous to those of the N.W. of 

 France last described, present themselves in the West of England, Wales, and Scot- 

 land, striking in a direction of E.N.E. or N.E. ; whilst in Ireland, although the same 

 general direction is usually apparent, similar rocks form the surface in many portions 

 of the island. 



Cornwall and Devonshire present four principal mining districts : viz. that of the 

 West, including St. Just, St. Ives, Marazion, and St. Erth ; secondly, that of the West 

 centre, including Gwennap, Eedruth, Camborne, St. Agnes, and Wendron ; thirdly, 

 the East centre of St. Austell and Lostwithiel ; fourthly, the eastern district, from 

 Liskeard to Tavistock. Again, in Devonshire, there are the mines between Newton 

 and Exeter, and those near North Molton. 



The first two of these districts are the most important of the four in the number 

 and richness of their mines of copper and tin. The ores of copper, which consist almost 

 entirely of copper pyrites and vitreous sulphuret of copper, constitute very regular 

 veins, running nearly from east to west, and incased most frequently in a clay-slate 

 locally termed Villas, and belonging to the Devonian system of modern geologists ; but 

 frequently also in the granite, which forms a series of protuberances rising through 

 clay-slates, in an E.N.E. direction from the Land's End to Dartmoor. The tin, 

 besides being found in alluvial deposits or 'stream-works,' which are nearly all 

 worked out, also occurs in veins or lodes which have a general east and west direction, 

 the same held by numerous dykes of granitic porphyry ('elvan '), which appear to 

 have a close relation to the metalliferous veins. The tin ore in a few mines forms 

 also irregular masses (termed tin-floors and carbonas) which appear most usually 

 attached to the veins by one of their points. Some of the veins present the copper 



