46 THE MINERALS OF TASMANIA. 



yellow, but easily tarnishes on exposure, when it may 

 become iridescent, and is then known as " peacock ore.' 

 In practical mining it is often closely mixed with common 

 iron pyrite, in which case the mixture has a paler colour. 

 The two species may be easily distinguished by their 

 respective colouration and hardness. Chalcopyrite is com- 

 paratively soft, easily yielding to the point of a knife, 

 whilst the iron pyrites is not only much paler, but resists 

 being scratched. The paragenetic relations of chalco- 

 pyrite are well understood, as it is so often associated 

 with quartz, siderite, as well as with cassiterite. The 

 recent formation of this mineral is shown by the action 

 of thermal waters on objects containing copper. At 

 several springs in Central France, chalcopyrite has been 

 found on old Roman bronze coins. The sulphur in such 

 cases is supplied by the sulphates in the waters, which are 

 reduced to sulphides by the decomposition of organic 

 matter (Rudler). Copper, probably this ore, was known 

 to occur in this island as far back as 1822 (Evans' Descrip- 

 tion of Van Diemen's Land). It occurs, amongst many 

 other localities, at Mt. Maurice; Badger Head; Saxon's 

 Creek, in solid white quartz; Mainwaring Inlet; Cas- 

 cade River, with cassiterite and schist; auriferous at Mt. 

 Ramsay, with native bismuth in amphibolite ; Dial Range ; 

 Lake Dora, as an impregnation in schist; Mt. Heems- 

 kirk ; Scamander River, with galena and arsenopyrite ; 

 Blue Tier, with cassiterite ; Bell Mount ; Mt. Bischoff, with 

 berthierite and chlorophane ; Rosebery, with galena and 

 blende; Mt. Read, with galena, blende, and huascolite ; 

 Heazlewood; Colebrook, with pyrrhotite in the limurite of 

 the locality ; Savage River, with magnetite and actinolite ; 

 Mt. Pelion ; Mt. Balfour, with covellite ; Mt. Farrell ; but 

 the most commercially important occurrences are those of 

 a metasomatic nature in the vicinitv of Mt. Lyell. 



The most important sulphide ores of copper are the 

 following, viz. : — 



('oTnp(}}'itio7i. 



Cu Fe S Crystallographic System. 



Chalcopyrite 84-5 30-5 35 Cu Fe S,' Tetragonal 



Chalcocite ... 80 ... 20 Cuj S Orthorhombic 



Covellite 66-4 ... 33-6 Cu S Hexagonal 



Bornite 55-5 16-4 28-1 Cug Fe S3 Isometric 



Cubanite 23-3 41-3 35-4 Cu FCa S4 Isometric 



Pyrite 4()-6 53-4 Fe Sj Isometric 



A small proportion of the iron in the last is often 

 replaced by copper, in which case it may be considered a 

 poor ore of the metal. 



