94 M. DE Hoff's Geological '■ 



schist ; 2. Zechstein ; 3. gryphite limestone ; 4. fetid 

 limestone (stinktein) ; and 5. Rauhkalk.* The marno- 

 bituminous schist, when it does exist, always constitutes the 

 lower bed of this formation ; is remarkable for the metallic 



* A peculiar variety of alpine limestone is described under the name 

 of Rauherkalk, or Rauhkalk, M. Voigt was the first thus to particularise 

 and name it ( Praktische Gebirgskunde, p. 87). Its fracture is granular, 

 and it often appears penetrated by spathose particles ; its texture is 

 porous, full of cavities; these vary from the size of a pea to an inch in 

 diameter; its name arises from the harshness of its touch. Dr. Jordan 

 has given a new description of it in his Mhieralogische Reise Bemer- 

 kungen, p. 57 ; he refers it to stinkstein, but believes it different from 

 that he has described under the same name of Rauhkalk, (Mineralogische 

 und chemische Beobachtungen, p. J 18), which exists on the south of the 

 Hartz, and in which occurs the cavern of Einhornloch, near Schartzfeld, 

 M. Haussmann describes this limestone of Schartzfeld, under the name 

 of Blasiger Floetzkalkstein, and considers it as above the ancient secondary- 

 gypsum, and consequently as posterior to the alpine limestone (zechstein) 

 situated beneath the gypsum ; he says nevertheless that there appears to 

 be a passage from the stinkstein to the Blasiger floetzkalkstein or rauhkalk 

 of Jordan. (Nord-deutsche Beytreege zur Berg und htittenkunde, No. 2, 

 p. 100.) 



M. Freiesleben, in his interesting work on the copper slate of tlie 

 Mansfeld country, describes, under the name of Rauchwacke, a brownish 

 grey limestone, containing silex, sometimes bituminous, harsh to the 

 touch, full of strange shaped cells, occurring immediately above the 

 zechstein, that is, generally beneath the gypsum and stinkstein, and which 

 he considers as different from the rauherkalk of M. Voigt. 



The same name of Rauchwacke is given in the copper slate mines of 

 Rielffsdorf, in Hesse, to a limestone also of a smoke grey colour, and very 

 cellular, but which occurs above the zechstein, the ancient gypsum, the 

 stinkstein, and even, as it appears, the second gypsum, and the clay 

 accompanying it. This rauchwacke is theii very difTerent, geologically 

 speaking, from that of M. Freiesleben. 



We have thought it right to place these notices together, the discus- 

 sion of which would produce long developments, in order to call atten- 

 tion to the confusion that exists relative to the names of Rauhkalk, 

 Rauherkalk, and Rauchwacke, and to prevent the errors that it may 

 occasion. 



Jiote by the Translator. — In order to shew the analogies of the Alpine 

 limestone, &c. to the magnesian limestone, and new red sandstone of the 

 English series, I shall present the classification of the former scries 



