452 PROCEEDINGS OF SECTION C. 



a large extent replaces iron oxide. If the latter be the true explanation 

 of the observed facts, the name calciotantalite naturally suggests 

 itself as descriptive. 



Mount Francisco. — This locality is about 15 miles south-west of 

 Wodgina, and has only recently been discovered. According to accounts 

 of the field received in Perth, the ore occurs under similar conditions 

 to those which obtain at Wodgina. The mineral, however, contains 

 much less tantalum, being a manganocolumbite with specific gravity 

 5-73, equal to 23 per cent, of tantahc oxide. The pegmatite in which 

 the ore occurs is composed mainly of albite, orthoclase, and quartz, 

 with more or less muscovite and garnet. The columbite is in irregular 

 masses, in which parallel groups of crystals are often well defined. The 

 faces most commonly developed are a (striated), b, ar d u. Twinning 

 on e was observed in one case. Small parallel crystals are developed in 

 great numbers at times on the macropinacoid a. 



A little detrital ore has been obtained from this locality. It is 

 thickly coated with ferruginous clay, which is sufficiently adherent to 

 give a rusty-black color to the ore, even after hard scrubbing with 

 water. The actual ore itself does not apparently weather readily, as 

 careful cleaning reveals bright black faces. The ore has not travelled 

 far, as excellent crystals with sharp edges occur amongst it. 



Greenhushes. — The last locality to be described was almost the 

 first in which tantalum and niobium were recognised in Australia. It 

 is interesting also as being the scene of the first mining for tantalum 

 ore in the Commonwealth, a lease having been secured and worked in 

 1902 to provide tantalite for the Foote Mineral Company of the United 

 States. 



Greenbushes is situated in the Blackwood Ranges. The prevailing 

 rock on the surface is a laterite composed largely of bauxite, and com- 

 pletely concealing the underlying .primary rocks from view except 

 in a few isolated areas adjacent to streams. The country appears to 

 be mainly granite, traversed by dykes of diorite and pegmatite, all 

 foliated more or less strongly in places. Considerable quantities of 

 tin ore have been recovered from the streams and older gravels and 

 cements, smaller quantities from the pegmatite dykes and foliated 

 bands of greisen. 



In 1893 Mr. J. J. East, of the Adelaide School of Mines, in ex- 

 amining some alluvial tin ore from Greenbushes, turned his attention 

 to a mineral present in it, which had been looked upon by the miners 

 as " resin tin," or in some cases as scheelite. A few blowpipe tests- 

 revealed the fact that this mineral was a new compound of antimony. 

 It was therefore submitted for analysis to Mr. G. A. Goyder, who- 

 established the fact that it was a tantalate and niobate of antimony. 

 This new mineral species was subsequently named stibiotantalite. 



Although only present in the ores from the southern part of the 

 field, and even then in quantities not exceeding 1 per cent, or 2 per cent., 

 stibiotantalite threatened at one time to become a serious trouble to- 

 the tin miners, as the antimony from it found its way into all the 

 smelted tin, and reduced its value by about £10 per ton. It would 



