96 GEOLOGY OF MT. FLINDERS AND FASSIFERN DISTRICTS, Q., 



Chemical Composition : 



Norm: 



Quartz 2*34 



Orthoclase 15*57 



Albite 64-9S 



Acmite 3 'TO 



Diopside 2-16 



Hematite 4*16 



Hypersthene 1*10 



Ilmenite 0*46 



Sphene 4-31 



Water... _ 1-26 



100 04 



Chemical classification : Class ii., Order 5, Rang 1, Subrang 4. 

 Magmatic name : Umptekose. 



ri.20. Loc: The Elbow, Old Warwick Road, Little Liverpool 

 Range. 



Handspecimen : dark greenish-black, vitreous rock. 



Texture : hemicrystalline, with microlitic phenocrysts in a 

 glassy base. The fabric is hyalopilitic. 



Composition : the microlites consist chiefly of sanidine (perhaps 

 anorthoclase). Sparingly represented we have minute idiomorphic 

 grains of greenish, faintly pleochroic ^egirine-augite; black idio- 

 morphic grains of magnetite, and a little ilmenite; also a few rods 

 of zircon. The rest of the rock consists of a cloudy yellowish 

 glass, which, from its frequent display of feeble polarisation, is 

 probably undergoing perlitic devitrification. 



Name : Vitrophyric Trachyte. 



Note. — This rock was obtained beneath a sheet of basalt, over- 

 lying which there is a trachyte capping. The basalt is probably 

 a sill, for it seems to diminish in grain-size towards the borders. 



F1.27. Loc: Little Liverpool Range, eastern slope, on Old 

 Warwick Road, at an elevation of 2,000 feet. 



Handspecimen : a brownish-grey rock, with subconchoidal 

 fracture, and consisting of white felspar masses in star-like 

 groupings, embraced in a brownish matrix. 



