ORIGIN OF ERUPTIVE AND PRIMARY ROCKS. 341 



Trachytic porphyry, Impalpable fundamental mass with 



crystals of sanidine, &c. 



Perlite, Enamel-like mass — globular. 



Obsidian and pumice stone, Vitreous mass — impalpable to porous. 



Phonolite, Impalpable schistose, fundamental mass 



Andesite, Friable mixture of albite, oligoklase, 



hornblende and magnetic iron ore. 

 Tufaceous Trachytic Rocks.* 

 Name. 



Trachytic-breccia. 



Trachytic conglomerate. 



Trachytic tuff. 



Phonolotic conglomerate. 



Pumice stone tuff. 



Trass. 



Pumice stone boulders. 



Pumice stone sand. 



Alumstone. 



Massive Basaltic RocJcs.'f 

 Name. Mineral constituents and general characters. 



Dolerite, Augite and labradorite, granular, 



ph anero-cry stalline . 



Anamesite, Augite and labradorite, constituents 



crypto-crystalline. 



Basalt, Augite and labradorite, impalpable, 



crypto-crystalline. 



Nepheline dolerite, Augite and nepheline, granular to 



impalpable. 



Leucitrock, Augite and leucite, granular to impal- 



pable. 



Analcimite, Augite, labrador, analcime, do. 



Tufaceous Basaltic Rochs.\ 

 Basalt conglomerate. 

 Basalt tuff. 

 Piperine. 

 Palagonite tuff. 



The rocks above mentioned belong to a class, the igneous 

 origin of which is regarded by geologists generally, as controvert- 



* Naumann : Geognosie, p. 709. 

 t Cotta; Gesteinlehre, p. 34. 

 % Naumann: Geognosie, I." p. 712. 



