116 PROCEEDINGS OF THE ROYAi, SOCIETY OF QUEENSLAND. 
‘ 
Andesite from Portion 1663, Parish of Wildash, Eight 
Mile Creek. This is a light-grey slghtly porphyritic 
type, which has a specific gravity of 2-747. Under the 
microscope small phenocrysts of plagioclase up to 1-25 mm. 
long are seen set in a hyalopilitic groundmass. Fluxion 
structure is well developed, and in the groundmass there 
are granules of augite up to 0-25 mm. in diameter. These 
eranules also occur as inclusions in the felspar phenocrysts. 
There is much alteration, calcite and epidote being 
abundant. This rock has been analysed, and the results 
may be seen in Table [. (Micro. 361.) 
Andesite from the east of Portion 1179, Parish of 
Wildash, Eight Mile Range. In the hand specimen the rock 
appears light-grey in colour and has abundant phenocrysts 
of milky-white plagioclase and dark augite set in a grey 
base. Under the microscope the phenocrysts show much 
zoning ia some cases, and those which are not zoned give 
an extinction angle indicating basic andesine. ‘The 
plagioclase phenocrysts range up to 3 mm. in length and 
the augite crystals up to 1 mm. long. The latter are usually 
fresh and often show twinning. The phenocrysts of 
plagioclase are more frequently zoned and perhaps more 
basic than in some of the other andesites. This andesite, 
however, is representative of a great thickness of material. 
The groundmass is rather of the pilotaxitie type and 
distributed through it are abundant granules of magnetite. 
Density 2-639. (Micro. 394.) 
BASALTS. 
These are not at all abundant, but they are always 
very dense, fine-grained, and rather platy in character. The 
following one, which has been analysed and whose analysis 
is given in Table I, may be taken as typical :— 
Basalt from centre of portion 2161, Parish of Wildash, 
Fight Mile Range. In the hand specimen it is very compact 
and heavy, having a density of 2-847. It is very fine 
grained and weathers to a deep-brownish soil. Under the 
microscope one notes its hemierystalline nature with a 
hyalopilitic groundmass showing marked fluxion structure. 
Throughout the field there are occasional lath-shaped 
crystals of medium andesine (Ab,,—An,,) and _ stout 
crystals of augite. These are set in a mass of crystallites of 
plagioclase, augite, and magnetite. (Micro. 364.) 
