MINES.

183

a place called Btirraco de Stanno. Some veins of the same metal were discovered in 1787,near Monte-Rey, in the south of Gallicia. They were fully two yards thick, and wereincased in granite. This province presents also deposites of sulphuret of antimony.Some analogous ores are found in Castille and Estremadura . Lead ores were worked mthe last century not far from Mogadouro , on the banks of the Sabor, in the province ofTras-los-Montes, and near Longroiva on the banks of the Rio-Prisco. Mines of plum-bago occur near Mogadouro . There are also some iron mines in the same country nearFelguiera and Torredemnacorvo. They supply the iron-works of Chapn-tunha. Twovery ancient establishments of the same kind exist in the Estremadura of Portugal ;the one in the district of Tliomar, and the other in that of Figuiero dos Vinhoss: theyare supplied by mines of red oxide of iron, situated on the frontiers of this province andofBeira. One deposite of quicksilver ore occurs at Couna in Portugal . At Rio Tintoin Spain, on the frontiers of Portugal , there is a copper mine which produces about33,000 libs, avoird. of this metal per annum. The ore is a copper pyrites. The moun-tains in the environs of Oporto present everywhere indications of the ores of copper andother metals; and it appears that all this part of the peninsula is in general rich in me-tallic treasures, but that the want of wood prevents their being mined to advantage.

Resides, many of the deposites which originally existed there must be in a great meas-ure exhausted. It was in these countries chiefly that the gold and silver mines lay,which the Carthaginians and Romans worked with so much advantage, and contestedin so keen a manner. Near Loria (the ancient Numantium), Azagala, and Burgos,considerable vestiges of the ancient workings may still be seen.

MINES OF BRITANNY.

Britanny has hardly a better share in mineral wealth than the countries we have justPassed in review. There exist in it at this moment only two important exploitations;Which are, the lead mines of Poullaouen and Hnelgoat, situated near Carhnix. The mineof Huelgoat, celebrated lor the plomb-gomme (hydro-aluminate) discovered in it, isopened on a vein of galena, which traverses transition rocks. The workings have sub-sisted for about three centuries, and have attained to a depth of 220 yards. The vein ofPoullaouen, called the New Mine, was discovered in 1741. It was powerful and veryrich near the surface ; but it became subdivided and impoverished with its depth, notwith-standing which the workings have been sunk to upward of 180 yards below the sur-face. In these mines there are fine hydraulic machines for the drainage of the waters, withwheels from 14 to 15 yards in diameter; and water-pressure machines have been recentlyinstructed. The mines employ more than 900 workmen, and furnish annually more than1)200,000 lbs. avoird. of lead, several thousand pounds of copper, and 2,000 marcs, or1)034 lbs. avoird. of silver. These are the most important metallic mines of France .Several veins of galena exist at Chaleliiudren, near Saint-Briex, but they are not workedat present. There is also one at Pompean, near Rennes , which has been worked to adepth of 140 yards, hut is in like manner now abandoned. It affords, besides thegalena, a very large quantity of blende (sulphuret of zinc), of which attempts are makingto take’ advantage. There occurs, also, a lead mine at Pierreville, department of theChannel, in a formation connected with the system of Britanny. It is opened on a veinWhich traverses a limestone pretty analogous to that of Derbyshire. The same depart-ment presents a deposite of sulphuret of mercury at Menildot. A few years ago, somelin ore was discovered at Pyriac, near Guerande, in the department of the Loire Inferi-eur, but the researches since made to find workable deposites have been unsuccessful.

mine of antimony was worked at La Ramee, department of La Vendee . Several of thec °al deposites lately mined in the departments of La Sarthe, La Mayenne, and Mayenne-et -Loire , ought probably to be regarded as more ancient than the genuine coal measures.

Table of the production of the French mines, during the year 1832.*

Species of Mine.

Number ofmines.

Extent ofsurfaceconceded.

Number ofworkmen.

Production is inlOths of a ton.

Value of therough productin francs

Kilom. carres.

130

Melted antim.1-030,98

A-ntimony

16

93,8954

71-232,75

Copper

8

274,18

258

■Black copper1*376

247.680

Iron

131

1-051,391

8917

Rough ore15-814,690

3,630-806,81

Manganese

Gold

8

1

16,54

0-49

66

6-087

66-849,88

kead and silverZinc

33

1

614,23

6,80

1259

8-505

742-051

* (Annalcs des Mines, tom. v., 1834, p. 676.)