of Devonshire and Cornivall. 133 



Viviani relates, that the lamellar metalloidal diallage, as well as the 

 jade of Sauasure, are found in the serpentine mountains of the Apen- 

 nines between La Rochetta and Sassello, in eastern Liguria.* It 

 appears to form a subordinate bed in the composition of those small 

 -insulated hills, which are for the most part of serpentine, and which 

 -are scattered here and there in the great valley which separates the 

 southern extremity of the Alps from the Apennine chain. 



I was very desirous of discovering from whence came the vast 

 quantity of blocks, consisting of diallage united with the jade of 

 Saussure, which are met with, not only in the great valley of the 

 ■Rhone, but also in that distinguished by the name of the Bassin de 

 ■Geneve^ and I had the good fortune to discover it in 1806, in com- 

 pany with Mr. William Maclure, in the Visp-Kle'in-Thal in the Haut 

 Valais on the skirts of Mount Rosa, which is an assemblage of 

 •mountains of serpentine. The smaragdite, or green diallage, extends 

 here for the space of several miles, from the village of Saass (eigh^ hun- 

 •dredand eleven toises above the level, of the sea) ascending the Vispach, 

 as far as the neighbourhood of Mount Moro at Macugnaga, and very 

 near Meigeren, the most elevated village in Switzerland and the Va- 

 lais which is inhabited during the whole year. This rock is found 

 in the form of enormous rounded blocks, adhering to the ground, 

 and heaped close together ; it is sometimes only a mixture of green 

 diallage, jade, and a little red oxide of titanium; in other places it is 

 green diallage mixed with primitive marble ; but I did not find the 

 •metalloidal variety there. Serpentine is also the matrix of the schil- 

 lerspar of the Tyrol, and of that found at Baste or Paste, near Harz- 

 burg, at Mezzebergen in Moravia, &c.t 



* Journal de Physique, Octobrc" 1807. 



+ " i am disposed to confeiJor the hornblende of Labrador, the variety culled scIuIUt- 

 *' spar, and the smaragdite of Saussure, as oive and the same species, as well as tiie 



