BY H. I. JENSKN. 601 



W.113. Loc: Tooraweanali Mountains, sumnnit. 



1. Handspecimen dark greenish-grey in colour, almost aphanitic. 



2. Texture holocrystalline, even- and fine-grained witli pilotax- 

 itic fabric. 



3. Constituents (in order of decreasing abundance): felspar 

 occurs in lath-shaped sections, and appears to Ijelong to the 

 species anorthoclase. The aigirine-augite is a somewhat strongly 

 pleochroic variety changing from light leek-green to dark green 

 and greenish-yellow. It occurs in needles and prismatic grains 

 with frayed ends. Biotite in irregular fragments is present in 

 the same proportion as segirine-augite. As accessories we find 

 magnetite and ferriferous decomposition-products. 



4. Name : Pilotaxitic Biotite ^girine-Trachyte. 



5. Note : biotite occurs in varying, usually very minute pro- 

 portions, in most of the dark-coloured trachytes in which the 

 main femic constituent is segirine-augite. These trachytes are 

 closely related to and graduate into andesites. 



W. 117. Loc: Naman Ledges opposite Black Mountain on 

 LTargon Creek. 



1. Handspecimen dark greenish in colour, with even fracture, 

 silky lustre, and aphanitic grain-size. 



2. Texture as in W.113. 



3. In composition it differs from W.113 in that biotite is 

 exceedingly rare; and it contains a few irregular masses of 

 dolomite, wliich probably represent infilled vesicles. 



Name : Pilotaxitic ^girine Trachy-Andesite. 



VV.9. Loc: Timor Ledges, Warrumbungle Ptange, one mile 

 north of Timor Hock. (Plate xxx., fig. 5). 



1. A dark aphanitic, silky rock, with even fracture. 



2. In texture like W.117. 



3. Composition as in W.117, but there is no dolomite, and a 

 little chlorite is present. The chlorite probably represents 

 altered a;girite or glass, and occuis in almost isotropic patches 

 with a fibrous structure. 



