small amount of iron ores and a great richness in ferro- 

 magnesian minerals, viz. olivine, hypersthene and enstatite 

 augite. The following table shows the mineral composition, 

 the rocks being arranged approximately in order of their 

 basicity: — 





7 



8 



f 



. 9 



f 



10 



f 



11 



t 



12 

 ■fc 



13 



14 



15 



16 



Olivine 



t 



Hypersthene ... 



t 



t 



t 



t 



t 



t 



t 



- 



- 



- 



Enstatite-augite 



- 



f 



t 



f 



T 



t 



t 



f 



t 



- 



Augite... 



- 



- 



•f 



f 



- 



t 



t 



- 



t 



t 



Pyroxene-perthite 



- 



t 



- 



f 



f 



- 



t 



- 



f 



f 



Hornblende 















* 



- 



f 



t 



Biotite... 



* 



* 



- 



tt 



* 



— 



* 



* 



* 



* 



Iron ores 



f 



* 



t 



t 



* 



* 



•*• 



f 



t 



t 



Apatite 



* 





- 



■fc 



- 



- 



- 



- 



* 



t 



Plagioclase 



f 



t 



t 



T 



T 



f 



t 



t 



T 



t 



Orthoclase 



■* 



* 



- 



* 



* 



-- 



- 



— 



* 



f 



Quartz... 









- 









* 



f 



f 



f An important constituent. # A minor constituent. - Absent. 



7. Near Camp 9, 23/6/91. 8. Hills near Camp 5, 20/6/91. 9- 

 ZigZag Range, 15/7/91. 10. Near Camp 8, 23/6/91. 11. Thirteen 

 miles west of Depdt I, 19/6/91. 12. Cavanagh Range. 13. Cavanagh 

 Range, 29/7/91. 14. Near Depot I, Cap of Range two and a half 

 miles distant. 15. Cap of Granite Range, Depot I, Camp 4, 9/6/9? . 

 16. Cavanagh Range, 21/7/91. 



The above table displays the interesting fact that while 

 orthoclase and biotite are present in almost all the rocks, 

 hornblende appears only in the acid rocks concomitantly 

 with the disappearance of olivine. 



The iron ores are seldom abundant, and exhibit variable 

 relationships. In No. 7 they are quite idiomorphic to 

 hypersthene and orthoclase, but present a broken outline 

 towards plagioclase, to which they appear to be posterior. 

 In other cases they are distinctly moulded on the plagioclase 

 and also on the pyroxenes. In No. 7 the species is ilmenite, 

 but in the others it appears to be a titaniferous magnetite, 

 to judge from the octohedral sections and the very slight 



