TABLE OF THE CLASSIFICATION 



OF THE 



MIXED ROCKS. 



BY ALEXANDRE BRONGNIART. 

 (Extracted from the Journal des Mines, No. 199, July, 1813.) 



Class I. CRYSTALLIZED ISOMEROUS 

 (ISOMERES) ROCKS. 



Character. The parts united by crystalline aggre- 

 gation, without either an essential predominant 

 base or portion, or a perceptible homogeneous 

 cement. 



Genus 1. FELSPATHIC ROCKS. 

 Char. Felspar is the essential constituent part. 



Species 1. GRANITE. 



Essentially composed of lamellar felspar, quartz, and mica, 

 nearly equally disseminated. 



Principal varieties. 



Common Granite Felspar, quartz, and mica, equally dissemi- 

 nated. 

 PoRPHYRiTic Granite. Crystals of felspar in small grained granite, 



b 



