65 



15. Tethrahedrite (Sulphantimonite of copper). 



Mr. R. H. Walcott, curator of the Industrial and Techno- 

 logical Museum of Melbourne, has kindly furnished rne with 

 the following note regarding this mineral : — " Occurs dis- 

 seminated through the ore of the Tasmania gold mining 

 company, Beacon sfi eld, associated with chalcopyrite, arseno- 

 pyrite, and pyrite. The gangue from this mine at times 

 contains a large amount of magnesian, lime, and iron 

 carbonates, probably as dolomite and siderite, but also 

 perhaps in minerals containing all three. Calcite appears to 

 be present in small quantity. The tetrahedrite contains little 

 or no silver, as far as can be ascertained." At the Hercules 

 mine, Mt. Read, some remarkably fine bunches and druses of 

 small but well-developed crystals of this mineral have 

 recently been obtained, associated with diallogite and barite. 



16. Uralite (A pseudomorphous hornblende with the external 

 form of augite). 



This secondary mineral has been optically detected in 

 petrographical work, and in the liniurite of the Colebrook its 

 presence is very pronounced. It is in all instances derived 

 from the alteration of augite, which, in this rock, occasionally 

 shows a more advanced alteration to actinolite. 



17. Vanadinite (Anorthovauadateof lead with chloride of lead). 



Occurs in groups of closely compact hexagonal prisms and 

 incr listing on sulphate of lead, of a deep rich reddish brown 

 to almost crimson colour with a resinous lustre. Magnet 

 silver mine, near Waratah. 



18. Zinkenite (Sulpha ntimoniate of lead). 



At Block 291 mine, North-East Dundas, some beautifully 

 developed crystals of this mineral have been obtained, some 

 few reaching nearly an inch in length. They belong to the 

 orthorhombic system, and commonly have the lateral faces 

 longitudinally striated with a low pyramidal termination. In 

 habit they are often grouped together, and mackles are 

 common. The specific gravity of the Dundas specimen is 

 5*16. Colour and streak, light steel grey. They occur 

 attached to siderite, with pyrite, tetrahedrite, and more 

 rarely crystals of argentite. 



19. Zinnwaldite (Lithia muscovite). 



Occurs in granite, and thus forms the common white mica 

 of the stanniferous rocks of the East Coast. 



