MINES 269 



MINES OP THE CENTRE OF FKANCE. 



The ancient formations, principally granitic, which constitute the basis of several 

 departments of tho centre and south of France, are hardly any richer in explorations 

 than tho districts mentioned at the end of the Black Forest. Many metalliferous 

 veins have been observed in the mountains of the Auvergno, Forez, Cevennes and 

 Lozere, but very few of the workings have attained to any importance. Most of tho 

 mining trials have been made near the eastern border of the mass of primary 

 formations, in a zone characterised by a great abundance of schistose rocks. 



At Villofort and Vialas, in tho department of the Lozere, and in some places 

 adjoining, several veins of argentiferous galena are worked which traverse the gneiss 

 and the granite. These mines, remarkable at present for the regularity of their work- 

 ings, employ 300 persons, and produce annually about 1,000 quintals of lead, and about 

 2,000 marcs of silver. 



Pontgibaud has been for some years the centre of mines of argentiferous load, 

 opened upon a group of north and south lodes intersecting a rock of gneissose 

 granitic character. Explorations have been commenced mostly where these lodes 

 were discovered in the valleys, as at Roure, Rosier, Mioch, Pranal, and Barbecot ; 

 and since 1853, by the joint exertions of an English and French proprietary, tho 

 mines have been raised to an important position, employing about 1,200 workpeople. 

 An unusual source of difficulty has been presented, in the form of strong emanations 

 of carbonic acid gas from the lode and the fissures of tho country, and which renders 

 it necessary to employ powerful ventilating machines, driven by water-wheels. The 

 presence of this gas is evidently connected with tho volcanic phenomena of tho 

 adjacent district, where streams of recent lava overlie the metalliferous granite, and 

 are not penetrated by the lodes. The Pontgibaud mines yield annually about 1,500 

 tons of lead, and 145,000 ozs. of silver. 



In the department of the Loire, the lead mines of St. -Mar tin-la- Sauvete south of 

 Roanne have been extensively opened on veins running N.W. and S.E. ; they are 

 now in English hands. 



The mountains of Ambert, on the west of tho valley of the Dore, Saint-Amand- 

 Roche-Savine and Giroux, as well as the mountains above Jumeaux, exhibit veins of 

 somewhat analogous character. 



At Malbosc and Bordezac (Ardeche), small lodes of antimony are seen in tho 

 slaty rocks. 



The city of Vienne, in Dauphiny, is built on a hill of gneiss, separated by tho Rhine 

 from the main body of the primitive formations, and in which veins of galena occur, 

 which are now imperfectly mined. Other lead mines of less importance are observed 

 at St. Julien-Molin-Molette, department of the Loire, and at Joux, dep. of the Rhone. 



At Chcssy, seven leagues N.W. of Lyons, mines, now worked out, were opened 

 upon an irregular deposit of copper ore, occurring at the contact of granite with 

 the lower sandy beds of the lias. The carbonates of copper were especially abundant, 

 and the azurito, or blue carbonate, from this mine is noted for the beauty of its 

 crystallisation. At Sainte-Bel, two leagues S. of Chessy, a very similar deposit of 

 copper pyrites, has also, after many years of activity, been abandoned. 



An abundant deposit of manganese ore, very irregularly worked, at Romaneche 

 (Saone-et-Loire) occurs in an analogous geological position ; as do also smaller bodies 

 of galena, calamine, and zinc-blende at Figeac, Villefranche, and Larclin. 



At Ecouchets, near Couches, tho oxide of chromium disseminated in the sandstones 

 termed arkoses, has been occasionally worked. Some important veins of zinc-blende 

 have been traced at Clairac, in the department du Gard, for above 1,000 yards from 

 N. to S. in tho beds of metamorphic lias. Iron ores of oolitic texture are largely 

 worked in the Jurassic and Neocomian rocks in various parts of France. 



Lastly, tin ore, accompanied by wolfram, has btjen found to occur in small lodes in 

 the district of Limoges, so well known for its china-clay, especially at Vaulry, a few 

 leagues NN.E. of that town ; and bismuth has recently been worked at Meymac, in the 

 department of Correze. 



MINES OF BEITTANT. 



In its geological conformation Brittany has a great analogy to its opposite neighbour, 

 Cornwall ; but notwithstanding the resemblance of its granites, ancient schists 

 (killas), and porphyries, it bears no comparison in the importance of its mineral 

 repositories. Tin ore has been found at two places, Piriac, a few miles to the N.E. 

 of the mouth of the Loire, where small quartzose veins, containing that mineral, occur 

 at tho junction of the granite and schists, and appear to have given rise to the alluvial 

 deposits of tin found near the mouth of the Vilaine ; and at Villeder, department of 



