30 THE MINERALS OF TASMANIA. 



in capillary patches, in which case there is usually some 

 pyrophyllite in close association. 



51. BiSMUTiTE (Hydrous Carbonate of Bismuth j. 



This mineral is only known in the pulverulent and 

 amorphous condition, resulting from the alteration of the 

 sulphide of the metal. It has been detected in small 

 coatings and blebs at Mt. Ramsay, North-East Dundas, 

 and at the Hampshire. At the Federal Mine, Heemskirk, 

 it has occurred intimately intermixed with quartz and 

 tourmaline. The Shepherd and Murphy Mine, Middle- 

 sex, has afforded by far the largest quantity hitherto found 

 in this State. It occurs as an accessory in a series of 

 small lodes in close association with, and at times contain- 

 ing a nucleus of bismuthinite, wolframite, and cassiterite 

 in a matrix of quartz, with which topaz is intermixed, 

 wollastonite, and occasionally fluorite. 



52. Blende. (See Sphalerite.) 



53. BoRNiTE (Sulphide of Copper and Iron). 



This mineral is also known under the name of erubes- 

 cite, but that given appears to have jDriority ; it is also 

 known under the vernacular term of "purple ore" or 

 " horseflesh ore." Empirically its copper contents are 

 55 per cent., much more than chalcopyrite, but less than 

 covellite (the blue sulphide) and chalcocite (the black 

 or gray sulphide). In crystallisation it is cubic, the crys- 

 tals being often confusedly aggregated together and com- 

 monly very irregular. Although this species is notably 

 profuse in this State the crystallised specimens are of 

 extreme rarity, and only occur very sparingly. When 

 freshly fractured the mineral presents a bronzy surface,, 

 which rapidly suffers tarnish on exposure ; it is often 

 iridescent. It usually occurs in the superficial workings 

 of the mines, but has been known to extend to consider- 

 able depths. It is probable that it originates from the 

 alteration of chalcopyrite by the action of circulating 

 waters containing copper sulphates. The most notable 

 occurrence m this island is in the Mt. Lyell district, where 

 it occurs as a replacement of the schists of the locality ; it 

 is here a most important ore of copper, and is extensively 

 mined. At this locality it is usually argentiferous and 

 auriferous, the silver contents occasionally being remark- 

 ably high. It also occurs at Mainwaring Inlet in quartz^ 



