Ifi-i PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 



From the extinction angles the felspar varies from 

 acid to medium andesine. 



The augite is highly titaniferous, as it has a distinct 

 violet tinge. The habit cf the crystals varies. It may be 

 in compact granules showing ophitic structure with the 

 plagioclase and containing inclusions of magnetite, or else 

 it may occur as long narrow wisps up to 5-75 mm. but still 

 showing ophitic structure. 



The m.0Gt interesting occurrence of augite, however, is 

 in the form of inclusions in the anorthoclase phenocrysts 

 when several granules in close proximity are optically 

 continuous, and in this way micrographic intergrowth of 

 the felspar and augite is indicated. 



Olivine in the form of clear rounded granules occurs 

 abundantly, and it is usually associated with a greenish 

 alteration product — possibly serpentine. 



Magnetite in small octahedral crystals occurs 

 abundantly throughout the ground-mass and as inclusions 

 in the phenccrysts and in the augite granules. 



CHEMICAL CHARACTERS. 

 T'or the purposes of comparison four other analyses 

 ,-are given in addition to that of the anorthoclase basalt. 



The second one — that of a tiow of oligoclase basalt from 

 the summit of Spicer's Peak in the Main Range, near 

 Cunningham's Gap — bears a striking similarity to the 

 .analysis under consideration. 



The third analysis of an olivine basalt from Blount 

 Lindsay is also of interest for comparison. 



The fourth analysis carried out by Miss Rose Scott, 

 M.Sc, in 1918, indicates the chemical character of the 

 normal basalt which occurs along the top of the Blaekall 

 Range. 



The fifth analysis is that given by R. A. Daly as the 

 average analysis of a basalt. 



It Avill be noted that the anorthoclase basalt has lower 

 alumina, more iron oxides, less magnesia, considerably less 

 lime, more soda, and twice as much potash as the ordinary 

 sub-alkaline basalt from JMcntville, which is characteristic 

 of the Blaekall Range as a whole. 



