75 



amphibole, alternating with colourless bands of quartz and 

 felspar, the latter mineral usually arranged as corroded ovoid 

 units. Thus is formed a laminated grey and white rock, and 

 various stages are observable, in which either of the bands 

 become predominantly developed. Though meta-igneous in 

 general appearance, there are grounds for ascribing a possible 

 meta-sedimentary origin for at least a portion of this series. 

 As far as a mile across the strike beyond this are garnet-mica- 

 quartz-felspar schists passing further south into grey gneiss, 

 composed of granulated quartz and felspar, with a little 

 biotibe only. Coarse pegmatite dykes are abundant, often 

 carrying tourmaline and haematite. 



North-west of the metamorphosed marble belt, in the 

 vicinity of Wadella Springs, much pegmatitic tourmaline- 

 bearing granite, forms conspicuous dykes amongst schists and 

 granulites. Eight miles further west, near Chinmina and 

 Cockaleechie, outcrops of quartz-felspar-schist and gneissic 

 granite types were observed. 



IV. Economic Mineral Resources. 



The character of the country, and the prospects so far 

 brought to light, augur much for the possibilities of economic 

 mining in Eyre Peninsula. 



Copper will, no doubt, always stand far ahead of other 

 mineral products. It is interesting to note that about one- 

 sixth the world's production of this metal is won in the Lake 

 Superior regions from rocks of approximately the same age 

 as the Tumby Bay series. 



The main lode of the Port Lincoln Copper Mine is the 

 type that should be further prospected for along the syncline 

 of metamorphosed marble. The ore in this formation is a 

 good quality copper pyrites, introduced as a metasomatic re- 

 placement of the limestone, which, in places, is mineralized 

 for a width of 20 feet along the strike from the underlay 

 side. A quantity of quartz occurs with the ore. Iron 

 pyrites is developed in slaty bands. 



South of the main ore-belt copper-bearing fissure veins 

 cross the schists, and, though always narrow and irregular, 

 have yielded a quantity of ore. 



Verv little mining has been done for other metalliferous 

 minerals. 



Much h'on ore, chiefly as a surface concentration from 

 iron-bearing schists, is scattered through the district gener- 

 ally, forming prominent hills, a usual feature in the weather- 

 ing of archaean schists. Such ores are both haematite and 

 limonite, and often contain a notable proportion of man- 

 ganese ; occasionally, the percentage of this latter element is 



