160 VOLCANIC AREA OF BAST MORETON, ETC., DISTRICTS, Q., 



up of numerous small lozenge- or lens-shaped areas. Again these 

 masses of carbonate may be merely amygdaloidal, the regular 

 outline being accidental. I am inclined to favour the former 

 view on account of the normative composition as calculated from 

 chemical analysis. 



(4) The order of consolidation was — 



1. Magnetite — : 



2. Hypersthene (1) 



3. Labradorite ; 



4. Diopside 



5. Andesine 



6 Augite (acmite) 



(5) Nomenclature. — This is a decomposed basic andesite, or 

 perhaps olivine basalt. The chemical analysis (Anal. x. p. 169) 

 places it in the alkalicalcic series. The magmatic name is Harzose, 

 and possibly of the parent rock, Shoshonose. 



(d) The Basalts. 



The detailed description of these rocks is unnecessary. Their 

 distribution is shown on the plan (Plate v.). An analysis was 

 made of basalt from Nindherry Range near Yandina, because of 

 the association here of basic rock with members of the trachy- 

 rhyolite series. The analysis shows that the basalt there is 

 fairly sodic, like the Sydney basalts (auvergnose). 

 Sp.No.66. Pilotaxitic Basalt. Loc: Mt. Mee. 



This rock is extremely dark, compact and fine-grained in hand- 

 specimen. Under the microscope it is seen to be holocrystalline, 

 even-grained, very fine-grained, with pilotaxitic fabric. The 

 essential minerals are felspar in lath-shaped microlites, isometric 

 grains of magnetite, and granules of augite. Apatite is present 

 in small amount. Greenish-blue, pleochroic chlorite, probably 

 after augite, occurs in fair quantity. 



Sp, No.140. Olivine Basalt Loc: Buderim Mountain. 



i. This is a dark compact rock, weathering more slowly than 

 most basalts, giving a red soil rich in iron ore. Red in weathered 

 specimens. 



