ON THE FORMATION OF CRSYTALLINE ROCKS. 271 



the same thing is true of some metalliferous deposits. The schists 

 containing copper of Mansfeld, the formations of lenticular iron ore of 

 the Youlte and of Privas, the beds containing jasper and metallic 

 minerals of the environs of Nontron, have been formed, as M. Gruuer 

 remarks, anterior to all the beds which now cover them.* This kind 

 o{ immediate ejngeny, in the very water. where these different deposits 

 have been formed, appears then to constitute a common character 

 with dolomites, with the reddish and variegated rocks, as well as 

 with many metalliferous beds. 



As another relation between these same formations I will further 

 remark, that in strata of various ages metalliferous deposits are often 

 associated with dolomite in such a peculiar way that there can be no 

 doubt that there is a common bond of origin between these two kinds 

 of deposits. We may cite as an example of this fact the masses of cala- 

 mine overlying the carboniferous limestone of Yielle-Montagne and of 

 Eifel ;t those of San Juan de Alcarras and of the province of Santan- 

 der, in Spain; the formations of the same metal in Silesia and Poland j:^ 

 the dolomite containing zinc, of England ; the small deposits of cala- 

 mine of central France, such as Durfort, (Losere), Combecave, (Lot,) 

 Alloue, (Charente ;) the formations of galena of Alpujarras; the mass 

 of iron ore of Vicdessos and of Canigou in the Pyrenees; the forma- 

 tions of the manganese of Nassau and those of Nontron, (Dordogne,) &c.§ 



Native sulphur, in its principal formations, is generally associated 

 either by the relation of cause to eifect or by the relation of effect to 

 cause, with deposits of gypsum. II We see this in Sicily, in several 

 parts of Italy, in the environs of Wieliczka in Poland, TT in Teruel in 

 Spain,** and on the banks of the Volga. ft If the sulphur came from 

 below in the state of sulphuretted hydrogen, as in the solfatares and 

 certain metalliferus deposits of Tuscany, where it is now daily being 

 deposited on the wood-work in the galleries of the mines, and was 

 there partially transformed into sulphate of lime by a more or less 

 perfect combustion ; or if the beds of sulphate of lime have undergone 

 an interior reduction, and by a well-known reaction produced sulphur, 

 under the influence of organic matters with which it is very often 

 associated, :j:| there is in either case a relation of metamorphism or 



* Annates des Mines, 4th series, vol. xviii, p. 91. 



f Max Braun, Zeitsckr d. Deulschen Geologischen Gesellsclia/t, Jarhrg, 1857 ; Bulletin de la 

 Socieii Geokgique, 2d series, vol. viii, p. 105. 



% Memoirs of Karsten, De Carnall, and others on this interesting country. 



§ We may include in this enumeration the beds of schist containing copper, of Mans- 

 feld ; the beds of sandstone, containing lead and copper, of the Moselle, which appear to 

 have been formed, like those cited above, before all the beds which now cover them. 



II Sojietimes also with alunite, and less frequently with sulphate of strontian, as in 

 Sicily. 



^ Annates des Mines, 4th series, vol. xviii, 1850. 



oc- The tertiary beds of Teruel, in which the lymneaare filled with sulphur, without de- 

 stroying the shell, and where this same substance has replaced the fibre in the stem of the 

 chara, are well known from the descriptions given by Esquerra del Bayo, Max Braun, 

 De Verneuil, and Collomb. 



ft Pallas, vol. i, p. 197 and 202 ; Eu^sia, by Murchison. 



\t It is doubless owing to a phenomenon of this kind that the sheathing of ships in some 

 of the African seas is attacked, as also the fact observed by Captain Wilmot on this coast 

 that there is deposited from the sea a mixture containing nearly an equal weight of organic 

 matter and sulphur. — {ImW.ut., March \'d, 1844.) 



