AUSTRALIAN MUSEUM SCIENTIFIC PUBLICATIONS Hodge-Smith, T., 1943. Mineralogical notes. No. VI. Records of the Australian Museum 21(4): 244–256. [22 December 1943]. doi:10.3853/j.0067-1975.21.1943.538 ISSN 0067-1975 Published by the Australian Museum, Sydney nature culture discover Australian Museum science is freely accessible online at http://publications.australianmuseum.net.au 6 College Street, Sydney NSW 2010, Australia MINERALOGICAL NOTES. No. VI.~ By T. HODGE-SMI'l'H, The Australian Museum. (Pigures 1-16.) Contents. Yfoljmmite, New South Wales. Apophyllite, New South Wales. Cassiterite, Emmaville, New South Wales. Phosphate Deposit, Cathcart, New South Wales. Microlite, Euriowie, New South Wales. Scheelite, Hatcher's Creek, Northern Territory. Tantalite, Finniss River, Northern Territory. Wolframite. New South Wales. (Figs. 1-10.) Two contributions have been made to the classification of the minerals of the woIframite series in New South Wales. Mr. George Smith (1936, p. 132) makes the general statement that "it then appears that wolframite which contains a larger percentage of manganese than iron has only been identified as occurring in one part of the State [apparently Yalgogrin-T.H.-S.] and the tungsten mineral so plentifully distributed should be classified as ferberite". He points to the difficulty in deciding when a mineral should be classed as wolframite or as ferberite and states that "it is difficult to draw a line of division between what are really variations of the one mineral". Mr. E. J. Kenny (1928, p. 178) states that: "The principal ores of tungsten worked in New South Wales are: Wolfram, tungstate of iron and manganese .. Other less important ores are: Ferberite, tungstate of iron; Hubnerite, tungstate of manganese. The ore from Torrington may be classified as 'Ferberite'." It is obvious from these two statements that there is no agreement as to the classification of the wolframite series in New South Wales. E. S. Dana (1892, p. 983) states that in woliramite, Fe:Mn chiefly 4:1 and 2:3, but varying from 9: 1 to 2: 3. F. L. Hess (Hess and Schaller, 1914, p. 37) defines ferbel'ite as "a monoclinic iron tungstate having when pure the composition FeWO,. It may contain not more than twenty per cent. of the hubnerite molecule MnWO;', and hubnerite as MnWO, con­ taining not more than twenty per cent. of the fer be rite molecule. While wolframite contains the hubnerite molecule in all proportions between twenty per cent. of FeWO, and eighty per cent. of MnWO., and eighty per cent. of FeWO, and twenty per cent. of MnW04• A. K. Boldyrew and E. J. Liasky (1929, p. 242) divide the series into hubnerite containing up to five per cent. of FeWO,; ferrohubnerite from five to twenty-five per cent. of FeW04 ; manganowolframite from twenty-five to forty per cent. of FeWO,; wolframite from forty to sixty per cent. of FeW04 ; ferrowolframite from sixty to seventy-five per cent. of FeWO,; manganoferberite from seventy-five to ninety-five per cent. of FeWO,; and ferberite more than ninety-five per cent. of FeWO•. * For No. V, see RE'CORDS OF THE AUSTRALIAN MUSEUM, xix, No. 3, 1934, p. 165. lYIIXERALOGICAL NOTES. NO. VI-T. HODGE-SMITH. 245 Both C. Doelter (1928, p. 846) and W. E. Ford (1932, p. 771) adopt the classification suggested by Hess and Schaller (1914, p. 37). E. T. Wherry (1914, p. 501) bases his classification on the C.I.P.W. classification for igneous rocks, thus: Permanganowolframite Mn:Fe 7:1. Domanganowolframite Mn:Fe between 7:1 and 5 :3. Ferromanganowolframite Mn:Fe between 5:3 and 3: 5. Doferrowolframite ........... Mll:Fe between 3:5 and 1: 7. Perferrowolframite .......... Mn:Fe 1: 7. He urges that none of these names, including the names of the end-members, should be used as mineral names for arbitrarily partitioned off portions. This leaves the names hubnerite for pure MnWO., ferberite for pure FeWOi , and wolframite for the remaining members of the series. From the above brief review of the various classifications it will be seen that there is considerable difference of opinion as to the proper division of this series of tungsten minerals. This is what might be expected, as any division must be necessarily :arbitrary. If the majority opinion is taken from the above outline, then the classification of Hess and Schaller would be adopted, but, as Wherry very clearly points out, such a ·classification is mineralogically quite unsound. Taking plagioclase as perhaps the best known example of an isomorphous series of two molecules, it is found that the names of the end members, albite and anorthite, are used as names for the molecules NaAl2Si3 0 8 and CaAI,Si,Os respectively. The inter­ mediate series are divided artificially into a number of members which are easily .distinguishable without recourse to chemical analysis. These divisions play a very important part in the classification of rocks and are therefore useful. This well established division of the intermediate series of the plagioclases is mineralogically unsound, but can be defended on the grounds of utility and ease of determination. Applying these principles to the wolframite series, the insistence of Wherry on the use .of the names hubnerite and ferberite for ·the end members only is confirmed. Any division should apply only to the intermediate members of the series. The only method of determining anyone of them is by careful chemical analysis. Schaller has shown the difficulty of interpreting the analysis and the same difficulty exists in regard to the New South Wales analyses. The only locality in New South Wales where the mineral has been found well .crystallized is in the Torrington district. No crystals have been found with sufficiently bright and smooth faces to give signals that would be of any use in tracing fundamental .differences in crystal structure due to variations in the ratio of the two molecules. Even if such perfect crystals were 'obtainable it is doubtful whether the desired results could be established as the analyses show a varying content of tantalum and niobium. A. K. Boldyrew and E. J. Liasky (1929, p. 242) have shown that the streak of the minerals changes from pale brown to almost black progressively from the hubnerite to the ferberite end of the series. They claim that the composition of the mineral can be .determined by the colour of the streak to within fifteen per cent. of the molecular composition. The mineral from Rockvale near Torrington, New South Wales, containing .eightY-five per cent. of FeWO. cannot be distinguished by this method from that from Hogue's Creek, New South Wales, containing seventy-two per cent. of FevVO" and these two minerals would receive different names both under the Boldyrew and Liasky and the Hess and Schaller classifications. It is clear that this method is not accurate enough for purposes of classification. Other ordinary physical tests are equally unsuitable. It is obvious that, unlike the plagioclase series, the wolframite series cannot be divided into easily distinguishable members. Further, it cannot be claimed that any such division is of any grep,t practical use. A common method of indicating the composition of the feldspars is by the symbol AbnAnm • Such a method can be easily applied to the wolframite series by using the symbol FbnHum • The classification would then be: ImCORDS OF 'l'HE Al;STRALIAN M USEt:3L Ferberite: FeWO, (Fb). Wolframite: (Fe, Mn)WO, (FbnHum ). Hubnerite: MnW04 (Hu). The majority of chemical analyses of New South Wales wolframites published have been carried out to determine only the amount of tungstic oxide present. In order to obtain somewhat better data the late Mr. H. P. White, formerly Chief Chemist, Department of Mines, kindly carried out four analyses on specially picked material, and Mr. R. 0. Chalmers, Assistant Mineralogist, completed three such analyses. The result of this work together with some previously published analyses is given in Table 1. TABI,E I. Uhemical Analysis oj New South Wales Woljmmite. COll­ stitucnt. 2 4 5 6 8 9 10 11 ]2 l4 15 --------------------- WO, 73 -67 75-48 74-90 76 50 76 -21 7764 I Nb,O,* 1 '95 0,52 Abs. I 0 36 0'31 1<'cO 18'85 20'07 20,44 16 88 16'53 18 76 lIfnO 5'2] 3'26 3'28 0'36 6'62 4'12 SiO, 0-39 0-29 0'17 , ! CaO 0'50 (J'48 Abs. 0'09 MgO 0,09 Trace Abs, H 20 0'26 Gangue 05,;? Al,O, Ei,O, SnO,_ 1---1---1------1---1---1---1---1---1---- lOO';l6 99'88100'27 99'76 'Including Ta,05 1. Illock 14, Torrington. Analyst H. P. White, 2. R. Smyth's }Iine, Torrington. Analyst R, 0. Chalmere, 3. Bismuth Mine, TOlTington. Analyst H. p, White (Smith, 1926). 4 . .Tamee Mine, Torrington. Analyst H, p, White (Ann, Rpt. Mines, 1920, 126). 5. Deepwater, Analyst H. P. White, 6. Rockvale )[jue, Tungsten. Analyst H. p, White, 7. Rockvale Mine, Tungsten, Analyst H. P. White (Ann. Rpt. Mines, 1919, 186). 8. Hogne's Creek near Dnndee, Analyst R. 0, Chalmers. 9. Glen Eden near Glen lImes, Analyst R. 0. Chalmers. ]0. Inverell. Analyst A. l,iversidge (Liversidge, 1882, 42). 11. Waukeroo, Yanco Glen, Barrier District. Analyst H. P. White, 12. Restdowll Mine, Yalgogrin, Analyst H. p, White (Ann, Rpt. Mines, 1920, 12(». 1:1. Pulletop. (Ann. Rpt, Mines, 1908, 183.) 14. Theoretical composition of ferbefite, ] 5, Theoretical composition of hubnerite. The presence of niobium and tantalum in all the later analyses carried out by White and Chalmers is of interest because in_ some of White's earlier analyses he records the absence of these elements.