182 THE GEOLOGY OF THE CANOBOLAS MOUNTAINS, 



IdioQiorpbic magnetite grains, often enveloped by secondary 

 haematite, are present. Yellowish acmite occasionally forms tufty 

 aggregates. In these a nucleus of brown soda-amphibole (cossy- 

 rite) is sometimes seen. Yellowish isotropic material is present, 

 and may be partly glass and partly chalcedony. A few allot rio- 

 morphic quartz-grains, and grains of a colourless isotropic 

 mineral with high refractive index are occasionally present inter- 

 stitially. The latter appears to be fluorite. 



The order of consolidation, as worked out from this slice, 

 appears to be, 



*1. Zircon 



*2. Magnetite 



*3. Felspar 



^'4. Hc^matite 



5. Cossyrite? 



6. -^girine 



7. Acmite 



8. Felspar 



9. Quartz 



10. Fluor, chalcedony, I 



liuionite. haematite \ 

 Name : Quartz-Acmite-Trachyte-Porpliyry. 



No.X.6--lr. Porphyritic Trachyte (or Comendite). Loc: 

 Pilcher's Farm. 



Handspecimen : compact, light-coloured, yellowish-grey, por- 

 phyritic rock. 



Texture: holocrystalline, perpatic, with micro- to crypto- 

 crystalline, trachytic base. 



Composition : the main constituent is felspar. The other 

 minerals are acmite, iron ores, chalcedony, opal, and perhaps a 

 trace of glass. The dominant felspar is the usual anorthoclase. 

 Some corroded phenocrysts have the characters of cloudy ortho- 

 clase. One corroded mass appeared to consist of four differently 

 oriented parts, separated by wavy boundary lines; hence it is- 



* Intnitelluric. 



