120 PROCEEDINGS OF THE ROYxVL SOCIETY OF QUEENSLAND. 



This is confirmed by the location on the map of the 

 principal mineral fields of North Queensland. Commencing at 

 Rocky River and running our pencil south, we pass through 

 the Hamilton, Coen, Ebagoolah, and Palmer goldfields, the 

 O.K., Chillagoe, and Tate mineral fields, Einasleigh and 

 Kidston, and thence south-west through Gilberton, Woolgar, 

 and after a Cretaceous overlap, the Cloncurry field. On the 

 massif itself the areas offering most promise of new finds are the 

 AVoollagorang-Lawn Hills area on the border and those already 

 mentioned in the Territory — viz., the Tanami area and the 

 Tipper Limraen, Mc Arthur, Katherine, and Alligator River 

 districts. These areas and the border festoon will \aeld mineral 

 wealth for ages to come. 



Nature of Lodes on the Massifs and Cordillera Compared. — 

 The lodes of the ma^ssifs (i.e., in pre-Cambrian formations) are 

 frequently large and permanent. They vary from high grade 

 to low grade. ]\Iany have been tried in the Territory after the 

 richer surface ores have been worked out, and in numerous 

 instances the magnificent early yields justified more thorough 

 exploration of the deeper zones, although transport difficulties 

 made it unprofitable to work any but the richer ores. 



There is no doubt that, Avith improved communications 

 and transport facilities, mines like the Iron BIom^ (Yam Creek), 

 Mount Bonnie (Margaret River), Coronet Hill, Daly River 

 copper mine, Eureka, and Evelyn will be reopened and worked 

 for lower-grade sulphides. 



When that time comes it will be essential to have a study 

 made of the sulpliides occurring below the water level to deter- 

 mine in the case of each mine whether they are primary, or of 

 secondary origin. In an area of plateau movement it would be 

 quite possible for bodies of carbonate and oxide to exist below 

 a zone of secondary sulphides. This possibility, being of great 

 economic importance, deserves close study. 



The large permanent fissure lodes and shear zones of the 

 massifs are frequently gossan-capped, passing into massive 

 sulphides below. In the Cordilleran area a quartz matrix 

 predominates, both in the surface and sulphide levels. 



In the Palseozoic folded rocks of the Cordilleran area the 

 lodes themselves have been so disturbed, both by Palaeozoic 

 and later folding, that they are reduced to discontinuous 

 lenses. 



