PROCEEDINGS OF SECTION C, 



447 



have been collected from this locality. Many are not of the tabular 

 habit of the crystal described. All are, however, of low specific gravitv, 

 indicating a low tantalum content. One fragment has the radiated 

 spherical structure previously mentioned in connection with Moolyella. 

 The only associated minerals observed were quartz, tourmaline, and 

 albite. Granite is the prevailing rock in the locality. 



Green's Well. — The main workings in this district are situated at a 

 locality variously known as Green's Well, Mount York, and Chinga- 

 mong. They were first developed in 1905, and are situated in the same 

 belt of granite as extends from Thelemann's Find through Wodgina 

 to Mount Francisco. 



The original mine in this locality has been described ofhciallv in 

 the following terms :— " On M.L. 100 (0. T. Bell and party) a rubbly 

 felspar formation has been exposed for a few feet. This carries tan- 

 talite, but sufficient work has not been done to allow of an opinion as 

 to the richness of the lode. On McBeth's alluvial reward claim tanta- 

 lite can be easily seen in the gully that traverses the claim." 



A sample of dressed ore from Green's Well, brought to Perth by 

 Mr. A. Gibb Maitland, apparently consists of both stream and lode ore 

 in angular fragments from 1mm. up to 20mm. in diameter. A great 

 portion of it is more or less well crystallised, a few excellent crystals 

 being observed in it, of which the following are details : — ■ 



The sample, as a whole, assayed — tantalic oxide, 42-39 per cent. ; 

 niobic oxide, 21-09 per cent. ; metallic tin, 15-62 per cent. The mineral 

 itself varies from a columbite, with specific gravity 5-35, to a tantalite, 

 with specific gravity 6-84. For the most part it has a dull rusty-black 

 surface, but occasional crystals exhibit brilhant black metallic faces, 

 especially a. This face and b is often striated vertically. The only 

 associated mineral observed in any abundance is cassiterite. The 

 primary deposit from which the ore is derived appears from the above 

 description to be a typical quartz-albite pegmatite. 



The ore from Green's Well is characterised by the very variable 

 extent to which tantalum and niobium replace one another. In another 

 sample from here, individual crystals varied in specific gravity from 

 6-4 up to 7-7, indicating an approximate percentage of tantalic oxide 

 varying from 46 to 81. 



Wodgina. — By far the most important tantalum deposits in Aus- 

 tralia are those of Wodgina, situated in the Pilbara Goldfield. in lat. 

 21° 15' S., long. 118° 40' E., 90 tons of dressed ore having already been 

 shipped from this locality. 



