IJY H. I. JENSEN. G05 



We therefore have the following order 



Olivine 



Magnetite 



Felspar, 1st gen. 



^girine 



Felspar, 2nd gen. 



5. Name : Panidiomorphic Oiivine-Trachy-Andesite {Kerato- 

 phyre of Rosenbusch). 



Note : another slide of the same specimen showed, in addition 

 to the minerals already mentioned, an interesting brown mineral 

 highly pleochroic in colours from deep reddish brown to yellowish- 

 brown. It shows no trace of cleavage, but is highly corroded 

 and full of magnetite inclusions, some of which are undoubtedly 

 primary and most probably secondary. Fragments of it also 

 occur adhering to the mossy magnetite aggregates. Both are 

 probably secondary. The shape of the crystals of this brown 

 mineral suggests hornblende or hypersthene, and the inclusions 

 are arranged as in hypersthene. The mineral is probably 

 pseudobrookite secondary after titaniferous rhombic pyroxene or 

 hornblende. 



Chemical Analysis : Specimen W.22 is in physical appearance 

 very like W.l (trachy-andesite), and in chemical composition 

 these rocks are also very close. The Nandi rock is, however, 

 richer in ferric oxide and titanic acid. The excess of the latter 

 has combined with FeoO.^, and probably NagO and SiOo, to give 

 a femic mineral subsequently altered to pseudobrookite (?), leaving 

 an excess of FeO free to combine with MgO to form olivine. 



Magmatic name of W.22, Monzonose {cp. Tables i. and ii.). 



W.32. Loc: The Forked Mountain, near Coonabarabran. 



This rock resembles W.22 both macroscopically and micro- 

 scopically. However, it contains some beautiful aegirine-augite 

 phenocrysts and fine plates of red micaceous haematite which is 

 an original mineral. Acicular crystals of apatite are present. 



Name : Hypidiomorphic-granular Olivine Haematite Trachy- 

 Andesite or Keratophyre (Rosenbusch). 



