BY H. I. JENSEN. 



93 



Name : Phonolitic ^Egirine-Trachyte. 



Chemical composition 



SiO, 



FeO 



MgO 



CaO.. 



HaOlabove 100°). 



TiO, 



NiO 



MnO , 



Sum 100-40 



Norm: 



Orthoclase 26-69 



Albite 35-11 



Nepheline 7-67 



Acmite 8-32 



Sodium Metasilicate 3-42 



Diopside 11-00 



Olivine ,..,,. 2-74 



Ilmenite 3*80 



Water 2-26 



Order 5, Rang 1, Subrang 4. 



Chemical classification : Class ii. 

 Magraatic name : Umptekose. 



F1.22. Loc: Little Liverpool Range. 



Handspecimen : a dark greenish-black, utterly aphanitic rock^ 

 very abundant on the eastern fall of the Little Liverpool Range. 

 This rock passes into a microcrystalline rock similar to the 

 trachy-andesites of the Warrumbungle Mountains, and Fl.13^ 

 Mt. Flinders. Only the aphanitic variety was collected. 



Texture : microcryptocrystalline, perpatic ; the base being 

 barely resolved with the high power. There seems to be little or 

 no glass. 



Composition : a few m-icroscopic phenocrysts, visible with the 

 low power, consist of sanidine-like felspar. The base consists of 

 an even-grained mixture of sanidine or anorthoclase in lath- 

 shaped microlites; idiomorphic grains of greenish-brown, strongly 

 pleochroic segirine augite; minute idiomorphic magnetite grains, 

 and cryptocrystalline interstitial matter. The fabric is trachytic. 



Name : ^girine-Trachyte, dark variety allied to Trachy- 

 andesite. 



