502 DOMAIN XII. VOLCANIC. 



cavkies of a hard and compact lava, in the neigh- 

 bouring mountains of Trezza, on the hill of Cifali, 

 and in the neighbourhood of Paterno, disposed in 

 beautiful starry crystals, formed of splendid py- 

 ramidal plates, more or less transparent, united in 

 the centre ; diverging sometimes with aggregated 

 rays, sometimes with distinct, and of various 

 length ; sometimes they are fascicular. But the 

 calcareous spar assumes a vast number of forms, 

 of which it is capable. In the heaviest and most 

 compact lavas of the rock of Motta, the cavities 

 v concealed in the mass, and which were formed 



while the paste was in a kind of ferment, are lined 

 with the same substance, covered ^ith many mi- 

 nute globules, but not visibly crystalised ; and I 

 have found it in the same form in the lava on the 

 high summit of the mountain of S. Vennera. 



" This calcareous spar may be said to be always 

 white ; but the iron proceeding from the decom- 

 position of lavas, often tinges it with various co- 

 lours, from blood-red to deep brown. I have 

 found some at Favarotta, near the lake of Palici, 

 which could not be distinguished, except by the 

 chemical test. 



" At no great distance from the mountain of Pa- 

 terno, there is a vast heap of large masses of lava, 

 containing crystals of felspar, where there are 

 some cavities filled with calcareous spar in bright 



