1 .32 Dr. B E-R G E R on the physical Structure 



one or two rocks in different countries, which ahnost always accom- 

 pany serpentine. 



It is not in Cornwall alone, that dial'.age is found in the immediate 

 vicinity of serpentine. It is found on Mount Musinet, t\vo leagues 

 west of Turin, a mountain almost entirely composed of a hard green- 

 ish serpentine. The mineral named after Saussure, Avhich he him- 

 self calls smaragdite, is the green variety of diallage united with 

 jade. The semiopal or hydrophane is found in a subordinate bed 

 in the same mountain.* I am sorry to say that this last mineral 

 becomes daily more rare ; I was not able to procure on the spot a 

 single well characterised specimen, after employing several hours in 

 searching for it. 



I found on Monte Baldissero^ in the Circle of Ivrea, the metalloidal 

 diallage, accompanied also with semiopal, nearly in the same geolo- 

 gical position as on Mount Musinet ; the only difference is, that the 

 rock which forms the mass of the mountain approaches more to the 

 nature of steatite than of serpentine. I also found in a vein on Monte 

 Baldissero a white earth in rounded mamillated masses, which used to 

 be taken for pure alumine, but which Giobert has shewn to be mag- 

 nesia, f It is used in the manufacture of porcelain, 



* Voyages dans des Alpes, § 1313. 



+ It contains according to this chemist, 



Magnesia . . 



68 



Carbonic acid . 



. 12 



Silica . . . 



. 15.60 



Sulphate of lime 



1.60 



Water . . , 



. 3 





100.20 





Journ. des Mines, No. US 



