PROCEEDINGS OF SECTION C. 453 



appear to have almost disappeared from the ores raised in recent years, 

 only occasional very small fragments being seen in the concentrates. 



In 1900, at the time when the author was examining some of the 

 antimonial tin ores with a view to suggesting a method of treatment, 

 trouble was again experienced at Greenbushes with a second class of 

 concentrates. Some apparently clean tin concentrates from alluvial 

 ground refused to yield up any tin. either in the assay pot or in the 

 smelting furnace. Several samples of this mysterious ore were for- 

 warded to the author, and proved to be tantalite of the normal iron 

 variety. No other tantalum minerals have so far been detected at 

 Greenbushes, except a doubtful new species, a hydrated tantalate of 

 antimony, which will be described later. 



Very little lode mining has been done at Greenbushes, either 

 for tin or tantalum. The total tantalum ore exported — 2| tons — 

 having been obtained almost exclusively from alluvial workings. The 

 principal lode workings are at the head of Bunbury Gully, on mining 

 lease 369 (Enterprise), where there is an ore body 18in. wide, consisting 

 of a crushed rock composed almost wholly of pale-green mica with 

 accessory quartz, tourmaline, cassiterite, and tantalite in fragments 

 from the size of sand up to an inch in diameter. Overlying the lode is 

 12ft. of alluvial, carrying fine and coarse tinstone and tantalite. 



On mining lease 379 (Galtee More), one mile further south, a 

 decomposed lode of apparently similar character carries tin and tanta- 

 lite. Some lode tin concentrates from mining lease 56 (Amanda), 

 lying between these two, was found to yield on assay 5-5 per cent, of 

 mixed tantalic and niobic oxides. This ore is described as coming from 

 a weathered tourmaline bearing dyke. 



The alluvial tantalite at Greenbushes occurs principally in Bunbury 

 and Floyd's pullies, in fragments from the size of sand grains up to 

 lumps 131bs. in weight. Its composition is not very variable, and, as 

 shown by the following analysis of a typical fragment, it is a high-grade 

 ore, occurring, unfortunately, in very limited quantities. 



Tantalum pentoxide 80'61 



Niobium pentoxide 2-50 



Tin dioxide 1-51 



Titanium dioxide '71 



Tungsten trioxide "13 



Water combined 'H 



Iron protoxide 10-89 



Manganese protoxide 3*78 



Nickel protoxide '02 



Lime Nil 



Magnesia "19 



Cerium and yttrium oxides Nil 



100-48 

 Specific gravity 7-74 



This specimen, Uke all others from Greenbushes, showed no traces 

 of crystal faces but exhibits an ill-defined cleavage. Dr. G. F. Kunz 

 reports that its radio-activity is less than 0-02 times that of uranium. 



