BY C. A. SUSSMILCH AND H. I. JENSEN. 191 



ANALYSES. 



General Remarks. — From the foregoing petrological sketches 

 it is clear that the Canobolas area is an alkaline petrological 

 province. The minerals characteristic of each rock-division 

 represented here are, generally speaking, the same as those met 

 with in the Nandewar and Warrumbungle rocks. 



The rock-types vary from the very acid coraendites and pan- 

 tellarites, to basic melilite-basalts, but all are derived from a 

 magma extremely rich in AlgOg, TiOo, and Na^O. 



t Owing to loss of mixed alkali by spurting, the total alkali was estimated 

 by difference, and divided between K.^O and Na.^0 in the experimentally 

 determined ratio. 



