xviii M. Brongniakt's Table 



Principal varieties. 

 Compact E The structtire compact with mica and gar- 

 nets, — no distinct crystals of felspar. 

 (Klingstein, WerneTf — The rock of Sanadoire 

 in Auvergne, — Coasme near Rennes.) 



Schistose E A fissile structure with a dense texture, &c. 



PoRPHYRiTic E Determinable crystals of either felspar or 



hornblende disseminated in the paste. 

 (Some hornstone porphyries, — ftotz trapp- 

 porphyr.) 



Species 2. LEPTENITE. {Hauy. Some weissteins, — 

 JlornfelSf Werner.) 



Base of granular felspar, containing mica and quartz as es- 

 sentially constituent parts. The structure granular. 



Species 3. TRACHYTE. (Haiii/. A kind of porphyry.) 



A fusible petrosiliceous paste of a dull aspect, enveloping 

 crystals of vitreous felspar. 



(Porphyritic roeks of the Drachenfels in the Sieben Gebirge. Mont 

 d'Or.) 



Genus II. WITH A CLAYSTONE (argilolite} 



BASE. 



Species 1. ARGILOPHYRE. {Thonporphyr, Werner.) 



A claystone base enveloping crystals of compact or dull 

 felspar. 



Species 1. DOMITE. (VonBuch. Xaz^a; of some mi- 

 neralogists.) 



Paste of harsh claystone, enveloping crystals of mica, &c. 

 (The Pay de Dome, — the Puy-Chopine in Auvergne, — the Isles Ponces.) 



Genus 12. WITH A BASE OF PITCHSTONE, 



or OBSIDIAN. 

 Species \. STIGMITE. {Vitchstone ox obsidian porphyry.) 



A paste of obsidian or pitchstone containing grains or crys- 

 tals of felspar. 



