196

MINES.

man; we allude to the clay-ironstone of the coal-measores. It is extracted in enormous quantities from the coal-basins of Scotland, Yorkshire, Staffordshire, Shropshire ,and South Wales.

Much of it is also raised from the coal strata of Silesia; and the French entertainhopes of finding a suppiy of this necessary ore in their own country. The iron-worksof England, which are supplied almost entirely from this iron-stone reduced with thecoke or coal, pour annually into commerce more than one million tons of cast and bariron, the value of which has been estimated at eight millions sterling; an amount full)'equal to the product of all the mines of Spanish America.

The shale or slate-clay of the coal-measures contains sometimes a very large quan-tity of pyrites, which, decomposing hy the action of air, with or without artificial heat,produces sulphate of iron and sulphate of alumina; whence copperas and alum arcmanufactured in great abundance.

The lead mines of Bleyberg and Gemiind, near Aix-la-Chapelle , are explored in fsandstone referred by many geologists to the red sandstone. The ore consists princi-pally of nodules, of galena disseminated in this rock. They are very abundant, and ojvery easy exploration. These mines produce annually from 700 to 800 tons of teamwhich does not contain silver in sufficient proportion to be worth the extracting. 2,0' ,utons of ore are prepared apd sold in the form of black lead dust (alqnifoux).

The manganese mines worked in the open air near Exeter , in England, occur in asandstone analogous to the red.

The calcareous formation which surmounts the coal-sandstone, called by geolog&j !zechstein , magnesian limestone, and older alpine limestone, contains different depositesmetallic ores ; the most celebrated being the cupreous schist of Mansfeldt, a stratum 0calcareous slate from a few inches to two feet thick, containing copper pyrites in sum'cient quantity to afford 2 per cent, of the weight of the ore of an argentiferous copP er 'This thin layer displays itself in the north of Germany over a length of eighty leagues,from the coasts of the Elbe to the hanks of the Rhine . Notwithstanding its thinn e '.and relative poverty, skilful miners have contrived to establish, on different points ®.^this slate, a number of important explorations, the most considerable being in the teflU.tory of Mansfeldt, particularly near Rotten burg. They produce annually 2,000 tonscopper, and 20,000 marcs of silver. We may also mention those of Hessia , sitm?*. 1 !near Frankenberg , Bieber, and Riegelsdorf. In the latter, the cupreous schist and iaccompanying strata are traversed by veins of cobalt, mined by the same system of ll - nderground workings as the schist. These operations are considerable; they extend, 1the direction of the strata, through a length of 8,700 yards, and penetrate downwarda very great depth. Three galleries of efflux are to be observed ; two of which P 0 ^their waters into the Fulde, and the third into the Verra. One of them runs about *yards below the most elevated point of the workings. These mines have been in ativity since the year 1530. Analogous mines exist near Saalfeld, in Saxony .

To the same geological formation must probably be referred the limestone which c ^tains the sparry iron mine of Schmlacalden, at the western foot of Thuringf' 1 '”'^where there has been explored from time immemorial a considerable mass of this ^known by the narrte of Stahlberg. The working is executed in the most irregular mner, and has opened up enormous excavations; whence disastrous ruins have taplace in the mines. It furnishes annually 4,500 tons of ore, which keep in play a £ rnumber of furnaces, where a deal of iron and steel is manufactured. . a0in c

At Tarnowitz, 14 leagues S.E. of Opjleln, in Siberia , the zechstein contains, W - eof its strata, considerable quantities of galena and calamine ; into which mines ^been opened, that yield annually from 600 to 700 tons of lead, 1,000 to 1,100 m a ^ c an jsilver, and much calamine. Mines of argentiferous lead are noticed at OlkutcmJaworno, in Gallicia, about 6 leagues N.E. of Cracow , and 15 leagues E.N.E. of an d

witz. Their position seems to indicate that they belong to the same formation,

possibly those of Willach and Bleyberg in Carinthia have the same locality. , e jnThere has been discovered lately near Cmfolens, in the department of la Char ’ tz .a secondary limestone, calcareous beds, and particularly subordinate beds of Q (j fwhich contain considerable quantities of galena. At Figeac also, in the departm ^le Lot, deposites of galena, blende, and calamine, occur in a secondaryla Vonlte, on the banks of the Rhone, there is mined, in the lower courses of the ^stones that constitute a great portion of the department of the Ardeche , a powerof iron ore. a ge,

It is in the zechstein, or in the sandstones, and trap rocks of nearly the samthat the four great deposites of the sulphuret of mercury, of Idria, the Palatimaden, and Hnancavelica, are mined. ’' ■ . ca ]led

The formation which separates the zeehstem from the lias ( calcain a grypM aI )dnew red sandstone and red marl in England, and bunter-sandstein, muschei r0 ckqnadersandstein. in Germany , presents hardly any important mines except thos