102 GEOLOGY OF MT. FLINDERS AND FASSIFERN DISTRICTS, Q., 



Minor constituents : ilmenite and titaniferous magnetite occur 

 in about equal proportions. Red iron-ores secondary after augite, 

 magnetite, and ilmenite also occur. A little serpentine and 

 leucoxene have also been noticed. Olivine has not been present 

 in the rock at all. 



Name : it is clearly an altered soda- and titanium-rich augite 

 analcite gabbro, and the weathered doleritic matrix must be 

 looked upon as a hypabyssal analcite-dolerite without olivine. 

 Near Teschenite. 



Soil : rich brown and black soils. 



Note : by the inclusions of one mineral in another, the order 

 of consolidation is found to be — 



1. Magnetite and ilmenite 



2. Augite 



3. Felspar — 



4. Analcite ■ 



Apatite is wholly absent, a rare thing in this rock-type. 



Summary. 



The Flinders volcanic rocks present the following peculiarities: 



1. They are nearly all intermediate, approaching phonolitic 

 rocks in chemical and mineralogical composition. 



2. They have partially crystallised at a depth Ijefore further 

 earth-movements caused their refusion and expulsion; hence the 

 coarsely crystalline xenoliths occurring in them. 



3. They invariably contain pneuniatoly^tic minerals, e.g., arfved- 

 sonite, zircon, rutile, etc. 



The Fassifern alkaline volcanic rocks have the following 

 features : — 



1. They^ ^'^»T iji basicity, from the most acid to the most basic, 

 ranging from comendites to what are practically ali-basalts 

 (alkaline basalts). 



2. Xenoliths due to inclusion of partially consolidated portions 

 of the same magma occur in both acid and basic rock-species. 



3. Evidences of pneumatolysis are abundant; in the commoner 

 rocks they are met with in the minerals zircon, rutile, arfved- 



