89 



indicated under (a) and (b). On the basis of mineral con- 

 tent, the ores may be classified as follows: — 



1. Massive pyrrhotite and chalcopyrite ores with 

 some pyrite, occasionally a little arsenopyrite and more 

 rarely magnetite and molybdenite. Galena and blende 

 have been found in a couple of instances. Free gold occurs, 

 but is rarely visible though the proportion runs from lo to 

 50 per cent, of the total gold content. 



2. Massive coarse grained pyrrhotite with but little 

 copper and gold. 



3. Pyrite and marcasite with arsenopyrite in veins 

 with possibly some galena and blende. This type is more 

 characteristic of the South belt, and silver may form an 

 important part of the values. 



4. Arsenopyrite, pyrrhotite, pyrite, molybdenite, a little 

 chalcopyrite, bismuthinite, and free gold, as impregnations 

 particularly in and around pegmatitic and aplitic dykes 

 of alkali syenite. 



5. Gold bearing quartz veins. 



Gangue. 



The gangue is chiefly more or less altered country 

 rock with some quartz and locally a little calcite. The 

 country rock may be altered to quartz associated with 

 secondary biotite in bands. Hornblende and chlorite are 

 extensively developed in places. Muscovite, tourmaline, 

 garnet, woUastonite and epidote also occur, and zeolites, 

 chiefly anthophyllite and chabazite, are frequently found. 



Ore. 



The typical ore consists of more or less altered rock 

 matter with reticulating veins and irregular masses of 

 pyrrhotite, and varying amounts of chalcopyrite with 

 perhaps a little quartz, the sulphides forming from 50 to 

 65 per cent, of the mass. There are all transitions from 

 the solid sulphides forming massive shoots of ore on the one 

 hand to rock matter or gangue on the other with little 

 apparent mineralization. In cases, however, lightly miner- 

 alized gangue may carry high gold values. 



The values are largely gold with some copper and a 

 little silver. The gold values do not appear to be dependent 

 on the presence of any one mineral, though in many cases 

 ore rich in chalcopyrite is rich in gold. The p^^rrhotite, 

 though gold bearing in some instances, is as a rule very 



