BY H. C. RICHxVRDS. 169 



the section as sub-ophitic patches approximately -2 mm. 

 in diameter. Small olivine granules which have been 

 altered occur sparingly through the section. Plagioclase 

 occurs in lath-shaped crystals averaging -3 mm. in length, 

 and it is either acid labradorite or basic andesine. The 

 iron-ore minerals occur both as small granules about -04 

 mm. in diameter, and as thin rods about 2 mm. long. 



The above rock is typical of most of the basalts on 

 Lamington Plateau, although there is a great variation 

 in the amount of olivine present, and also fluxion structure 

 is not always present. 



Phenocrysts of olivine with large crystals of plagio- 

 clase moulded on them are seen in some sections of these 

 rocks. 



Specimen 94. — Locality: Chinghee Creek, portion 69, 

 parish of Telemon. This is one of the flows from the first 

 eruption, and it is found below the rhyolite agglomerate. 

 In the hand-specimen it is a compact rock, which shows 

 occasional plagioclase phenocrysts. When examined micro- 

 scopically it is seen to be holocrystalline with very occasional 

 plagioclase phenocrysts set in a groundmass with plagio- 

 clase averaging -5 mm. in length, and showing a rough 

 fluxion structure. The plagioclase is both medium and 

 basic andesine, but the latter is the more abundant. {See 

 Plate XIV., fig 3.) Ophitic structure is very well 

 developed, and the enclosing augite by its violet colour is 

 apparently the titaniferous variety. 



Olivine granules which are altering into serpentine 

 are abundant, and they have an average size of -25 mm. in 

 diameter. Allotriomorphic grains and rods of iron-ore 

 are plentiful. The specific gravity of this rock is 2-76 

 and an analysis is given. Name : Basalt. 



Specimen 92. — Chinghee Creek, portion 67v, parish of 

 Telemon. This is one of the flows from the third period 

 of eruption, and rests on top of the rhyolite agglomerate. 

 It comes from Lahey's Cutting. The flow is very much 

 weathered, and it is a matter of difficulty to get a fresh 

 specimen. This rock is rather finer-grained than the pre- 

 vious one and contains more olivine, being particularly 



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