NOMES VII. AND VIII. 175 



HYPONOME I. 



Massive. 



HYPONOME II. 



Schistose. 



NOME VII. SLATE AND CHLORITE SLATE. 



This is rather a scarce transition, the latter 

 substance not being common. Slate also passes 

 into mica slate j and sometimes into the massive 

 substance described under the Mode Slate. 



- 

 NOME VIII. FELSITE AND BASALTIN. 



Dolomieu, in his able memoir on petrosilex or 

 felsite, trap, and roche de come, or magnesian 

 basaltin, observes that they are the chief bases of 

 lavas ; and thus entered into his consideration, 

 in forming a system of volcanic productions. 

 He then speaks of the various transitions of his 

 petrosilex or felsite*. 



* Journal de Physique, new series, yol. i. p. 259. 



