BY H. I. JENSEN. 167 



hypabyssal intrusions of a calcalkalic nature took place. The 

 hypabyssal rocks and contemporaneous lavas were intei'mecliate 

 in composition. The highly alkaline acid lavas followed. Lastly 

 came the basaltic extrusions which were sometimes inclined to 

 the alkaline series (auvergnose) sometimes calcic, but uniformly 



very ferriferous. 



Conclusion 



To recapitulate, then, the main results of my ehemico-petro- 

 logical work may be stated as follows: — 



(a) The alkaline nature of the petrographical province of the 

 Glass House Mountains has been established. This province has 

 been shown to extend far beyond the GlassHouseMountainsproper. 



(b) The nature of the blue amphiboles in the trachytes and 

 pantellarites has been determined by chemical as well as optical 

 examination, and evidence on both accounts has been found for 

 the existence of a chlorine-bearing mineral of the scapolite group 

 as well. 



(c) The importance of mineralisers like ZrO„, TiO„, S and F in 

 the production of riebeckite and cossyrite was first demonstrated 

 by Murgogi, and gets confirmation from my work. Chlorine, 

 however, has largely replaced fluorine in the pneumatolytic pro- 

 cesses of this area. 



(d) Evidence of a petrological character has considerably 

 assisted field evidence in establishing the sequence and relation- 

 ships of the hypabj'ssal and volcanic rocks. 



(e) Very interesting and rare schistose rocks with rutile, 

 glaucophane, anthophyllite, zoisite, and sillimanite have been 

 shown to abound around Mt. Mee. 



(/) The constant occurrence of nickel in the chemical analyses 

 hints at the district being nickel-bearing; and metalliferous 

 deposits of manganese, nickel and cobalt are likely to be found 

 amongst the serpentinous, gabbroic, and schistose rocks of the 

 D'Aguilar Range. 



Finally, I desire to express my cordial thanks to Dr. W. G. 

 Woolnough for his invaluable suggestions and help in the deter- 

 mination of the optical characters of rare minerals, especially in 

 the schistose rocks. 



