214 



or amphibole, is in general very rare at TenerifTe, 

 not only in the modern lithoid lavas, but also 

 in the ancient basalts, as has been observed by 

 Mr. Cordier, who resided longer at the Canaries 

 than any other mineralogist. Nepheline, leucite, 

 idocrase, and mejonite have not yet been seen at 

 the Peak of Teneriffe ; for a reddish gray lava, 

 which we found on the slope of Monte Verde, 

 and which contains small microscopic crystals, 

 appears to me to be an intimate mixture of 

 basalt and analcime * In the same manner the 

 lava of la Scala, with which the city of Naples 

 is paved, offers an intimate mixture of basalt, 

 nepheline, and leucite. With respect to this 

 last substance, which has hitherto been observed 

 only at Vesuvius, and in the environs of Rome, 

 it exists perhaps at the Peak of Teneriffe, in the 

 old currents of lava that are covered by more 

 recent ejections. Vesuvius during a long series 

 of years ^ has also thrown out lavas without 

 leucites : and if it be true, as Mr. Von Buch has 



belong, according to Mr. Karsten, to the pyroxene, augit. 

 Journal des Mines de Frieberg, 1791, p. 215. 



* This substance, which Mr. Dolomieu discovered in the 

 amygdaloids of Catania in Sicily, and which accompanies 

 the stilbites of Fassa in Tyrol, forms, with the chabasie of 

 Hauy, the genus cubicit of Werner. Mr. Cordier found at 

 Teneriffe zeolite in an amygdaloid which covers the basalts 

 ©f La Punta di Naga. 



f For instance in 1760, 1794, and 1805. 



