150 VOLCANIC AREA OF EAST MORETON, ETC., DISTRICTS, Q., 



(vi.) JEgirine Pantellarite. Loc: Skeleton Caves, Trachyte 

 Range. 



This is a holocrystalline, very fine-grained and compact rock of 

 a greenish colour and somewhat greasy lustre. It has a pilotaxitic 

 fabric, and consists essentially of sanidine (anorthoclase) and 

 segirine, with a few phenocrysts of a light bluish soda amphibole 

 (variet}'- of riebeckite), and some fine-grained dendritic aggregates 

 of cossyrite. There is a felsitic base. 



This rock was analysed (Anal. iv. p.lfi8), and was found to be 

 very acid and alkaline, having the composition of the family of 

 Pantellarites of Rosenbusch. The norm gives us the magmatic 

 name of liparose. 



(vii.) Riebeckite Comendite. Loc: Mt. Tibrogargan (Plate xiv, 

 fig,21). 

 This is a fine-grained, hypocrystalline, orthophyric rock, com- 

 posed of sanidine, riebeckite, a little glass, and felsitic base. 

 The riebeckite occurs in dendritic aggregates of minute crystals. 



(viii.) Orthophyric Trachyte (Comendite ?). Loc: North slopes 

 of Mt. Beerburrum. 

 This is a fine-grained, slightly porphyritic rock, resembling the 

 previous (vii.) closely, both in handspecimen and microscopically. 

 It is orthophyric, and consists of felspar (sanidine-anorthoclase), 

 and dendritic patches of a soda-hornblende, which is pleochroic 

 in colours from brown to bluish-green and yellowish-green. This 

 amphibole, therefore, seems to lie between arfvedsonite, barkevi- 

 cite, and cossyrite; and may be identical with Brogger's kato- 

 phorite. There is also a cryptocrystalline base. 



(ix ) Porphyritic JEgirine-.Riebeckite Trachyte. Loc. : Mt. 

 Beerburrum. 

 This porphyritic rock forms the main rock of the locality, and 

 has been described in my previous paper. It is porphyritic and 

 has a trachytic base. The felspar phenocrysts consist of anortho- 

 clase. In the base we have sanidine and oligoclase. .ZEgirine in 

 small needles, a soda amphibole (blue), probably riebeckite, and 

 a very opaque brownish amphibole, probably cossyrite, are 

 present in very small amount. 



