of Serpentine, Sfc^ in the Apennines. 190 



M. Viviani,* in 1807, when describing the mountain of 

 Dragnon and that of Montenero, gives very pxact details on 

 the structure and nature of the diallage serpentine, the cal- 

 careous diallage rocks, and the jasper composing it ; but 

 he does not speak of their relative position, and regards di- 

 allage rock as primitive. This opinion was then so deeply 

 rooted, that having remarked a serpentine crust which in 

 some places covered the argillaceous ground of the southern 

 slope of Montenero, he supposes that this mountain was 

 formerly, and on this side, in contact with that of serpen- 

 tine (p. 16), and M. Brocchi is disposed to admit this ex- 

 planation. 



M. Cordier, who visited this same mountain in 1809, and 

 who has given the mineralogical and statistical account of 

 the department of the Apennines,! having more attached 

 himself to the technical part than geological considerations, 

 has described the Montenero, the serpentines, the diallage 

 rocks (under the name of granite de diallage), the jaspers, 

 the manganese and brown ochre they contain, without ex- 

 plicitly speaking of the geological relations of these rocks 

 with the sandy limestone of the Apennines. 



He refers the diallage rock and all its varieties, the com- 

 mon schistose and diallagic serpentine, and the steaschist 

 to the primary class; and the secondary class, the jaspers, 

 the limestones, the marly schists, and blackish and calca- 

 reous slates worked at Lavagna, which afford a new proof of 

 the alternation of the micaceous calcareo-sandstones with 

 calcareo-argillaceous slates, marly schists, and limestones ; 

 he also refers to it the grey and blackish compact limestones, 

 with spathose veins, and even the marble named por/or, of 

 Porto- Venere. 



It was especially necessary for me to stydy the works, ob- 

 servations, and opinions of M. Brocchi, the geologist, who 

 has, of late, given the best exposition of the structure of the 

 Apennines. I fully appreciate the advantage I have had of 

 conversing with him on the subject of this memoir, and I do 



* Travels on the Apennines of Liguria, Genoa, 1807. 

 + Journal des Mines, No. 176, August, 1811. 



