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



the analysis, we may infer that the glaucophane here present is 

 like those of Rhodes, analysed by Foullon,* richer in ferric than 

 in ferrous iron. The high percentage of Fe._,0 3 also shows that 

 the epidote is highly ferriferous. 



The glaucophane of Sp. No. 106 is closely allied to actinolite. 

 It is greenish in colour, strongly p*leochroic in colours from 

 greenish-blue to light green and colourless, and never shows the 

 violet and purple tints visible in the pleochroism of Sp. No. 65. 



The occurrence of glaucophane in these rocks is interesting for 

 many reasons. Firstly, because glaucophane is a very rare mineral^ 

 and this is, perhaps, the first undoubted locality in Australia 

 from which it has been described. Secondly, because it is 

 usually found only in highly metamorphic Archsean formations, 

 and the Mt. Mee rocks have hitherto been considered by the 

 Queensland Geological Survey as not older than Carboniferous. 

 Thirdly, because of the occurrence of serpentinous rocks in the 

 South DAguilar Range, and the high nickel content of the 

 glaucophane rocks which call to mind similar associations in New 

 Caledonia; and, fourthly, they are interesting because of the 

 occurrence of riebeckite and arfvedsonite eruptives of a much 

 later age in the same district, showing that it was an alkaline 

 province in Palaeozoic times, and became so again in Post-Triassic 

 times. 



The glaucophane rocks are intimately associated with antho- 

 phyllite schists, greenstones and other hornblende schists on Mt.. 

 Mee, and with actinolite-cordierite and chlorite schists at Leacy's 

 Ck. From microscopic as well as from field evidence it is my 

 opinion that all these rocks are altered lavas and tuffs of a basic 

 character. The intense folding which has taken place in them 

 has led to the development of glaucophane, zoisite, cordierite,. 

 sillimanite and many other minerals characteristic of highly 

 metamorphic series. The actual glaucophane rocks probably 

 form the pipes whence the lavas flowed. 



The norm of the igneous rock from which the glaucophane- 

 schist may be derived has been calculated and stated (Norm.xii a).. 



* Sitzb. Akad. Wien, 1891, 100. 



