BY H. C. RICHARDS. 171 



thin lath-shaped plagioclase and augite crystals up to -5 

 mm. long, set in a pilotaxitie groundmass of augite, plagio- 

 clase, olivine and iron-ore. 



The plagioclase shows lamellar twinning and is acid 

 labradorite, Ab^-An^-, while the augite is seen to have a 

 marked violet tint. The iron-ore which is very abundant 

 and more or less aggregated into patches is seen to consist 

 largely of octahedral crystals, so that it is largely magnetite. 

 The olivine occurs as rounded granules averaging -15 mm. 

 in diameter. It is noticeable that ophitic structure is 

 entirely absent, also the ' ' granulitic " structure which one 

 finds in some of the flows and which indicates movement 

 after crystallisation. Name : DolcrUe. 



Si^ccimcn 124. — Locality: Canungra Creek, portion 21, 

 parish of Sarabah. This is a flow which belongs to the 

 tirst division of basic rocks, and is the only one of this 

 division in which columnar structure has been seen. The 

 rock in the hand-specimen is seen to contain abundant 

 phenoerysts of plagioclase and occasional crystals of 

 olivine. Microscopically it is hypoerystalline and consists 

 of sub-idiomorphic crystals of medium labradorite, AboAn,, 

 in size up to 3 mm. long but averaging 1-5 mm., and 

 rounded and corroded phenoerysts of olivine averaging 1 

 mm. in diameter, set in a groundmass of plagioclase, olivine, 

 augite, iron-ore and a brown glass. The augite does not 

 appear in two generations like olivine does. The plagio- 

 clase phenoerysts in many cases are very well zoned, and 

 the outer fringes are rather acid andesine. The plagio- 

 clase in the groundmass averages -3 mm. in length and is 

 fairly basic andesine. 



The brown glass is very cloudy and seems crowded 

 with small dots of iron-ore. The latter occurs as rounded 

 patches and as rods up to -2 mm. in length. This rock 

 is mainly characterised by the zoning of the plagioclase 

 phenoerysts. y.mne: Andcsitic hasalt. 



Specimen 116. — Summit Spicer's Peak. This rock is 

 a very compact dark-greenish one, and shows very occa- 

 .sional phenoerysts of olivine. Microscopically it has a 

 ■cryptocrystalline groundmass which seems to be mainly 

 felspar, although granules of augite can be seen. {See 



