DOMAIN IV. TALCOtfS. 



trap are commonly filled with calcareous spar; 

 while those of his rocke-de-carne, or Saussurite, 

 besides calcareous spar, often present a green 

 with steatite, steatite extremely ferruginous*. This feature, 

 with the occurrence of amianthus, and other 

 modes of talc, confirms the magnesian propen- 

 sity of this rock ; and as these green nodules 

 are also frequent in amygdalite, it is to be sus- 

 pected that the latter, to the base of which va- 

 rious denominations have been assigned, may, 

 when duly analysed, be found to belong to this 

 division. 



Dolomieu also considers the chlorite slate of 

 Werner, which often presents octahedral crystals 

 of iron, as intermediate, between the roche dc 

 come and the talcs ; while the former graduates? 

 from trap to serpentine. 



" In Tuscany there are frequent examples of 

 these passages of rochc de come to serpentine. 

 At Pietra Mala, on the ridge of the Apennines, 

 to the right of the road from Bologna to Flo- 

 rence, there is a mountain which presents all 

 the kinds of gradations between serpentine and 

 roche de corne, and the passage of the earthy 

 grain of this to the scaly texture of hornblende, 

 or corneus spathosus. This roche de corne, of a 



* Journal de Physique, 17Q4, p. 258. 



