Resources Tasmania

TASMANIA DEVELOPMENT REPORT 1993/21 AND RESOURCES

Mineralogical examination of some mineral samples from Tasmania, for the Tasmanian Museum and Art Gallery

by R. S. Bottrill and R. N. Woolley

The following samples. from the Petterd collection held by phosgenite in appearance, but was not tested due to its high the Tasmanian Museum and Art Gallery, Hobart, were quality. The was confirmed by XRD. examined to confirm the presence of several rare reported in Tasmania (Department of Mines. 1970). The X1115: "Phosgenite, Dundas, Tasmania" samples were examined stereomicroscopically and by This sample varies from white to a moderate purplish X-ray diffraction (XRD, with a Philips PW 17 IOIPW 1050 brown in colour. It is largely a coarse-grained crystalline automated X-ray powder diffractometer). The results of aggregate, with in vughs varying from bladed to these examinations are given below. fibrous aggregates. Much of the sample is smooth and etched or waterworn, and there is a partial red-brown X160: "Native , Mt Dundas, Tasmania" limonitic coating on some crystals. XRD indicates the This sample is grey and irregular to dendritic, and partly sample to be cerussite. decomposed. XRD indicated only and minor hydrocerussite, but the sample is slightly malleable and X1116: "Phosgenite, Magnet, Tasmania" there is probably lead metal present in its core. There is no The sample actually consists of two quite different matrix, and it is not possible to confirm the natural specimens. One (Specimen A) contains a large grey, occurrence of the sample. glassy, blocky, partly broken in a cavity in fine-grained, massive , with some massive to X624: " on galena, Magnet, Tasmania" crystallised cerussite. XRD indicates the large crystal to be phosgenite, but possibly with an expanded lattice. This sample was not tested by XRD due to the small number of crystals present. It does, however, greatly Specimen B contains bands of hard, porous, limonitic resemble matlockite from the type locality (Matlock, brown gossan; granular, sulphidic, white to creamy England: Burr, 1992). The matrix is also unusual for the coloured carbonate (?); coarsely crystalline stated locality (Magnet mine), with possible galena; and white to brown crystals (to a few millimetres). present. If it is from the type locality it would still be a very XRD indicates the presence of , and valuable specimen. siderite in the crystal crusts. The mimetite varies from white or colourless to a deep red-brown, the colouration X865: ", White River, Tasmania" probably largely resulting from the associated sphalerite This sample is a white, shaly-Iooking rock with a bright red and/or limonite, and crystals are hexagonal prisms and ochreous coating. The red coating contains, in approximate pinacoids with minor bipyramids. order of abundance: , hematite, chlorite, goethite and illite. The red colour is presumably due to hematite; there X1970: ", Magnet, Waratah, Tasmania" is no indication of any lead minerals present. Minium is This sample has a porous, vughy matrix of yellow-orange probably not a true mineral at any rate, usually being a powdery limonite, with scattered white quartz as blebs and result of mine fires or other man-made intervention. small crystals. Cavities contain fine drusy red to yellow crystals to about one millimetre in size. Some of these are X1114: "Phosgenite, Magnet, Tasmania" simple hexagonal prisms of mimetite, varying from pale yellow and transparent to opaque and red in colour. Coating This sample is of partly oxidised lead ore. The matrix is the mimetite, limonite and quartz are finer, bladed, opaque mostly coarse-grained galena, partly leached and coated in red "shark's tooth" crystals of . XRD confirmed places with black, non-crystalline (?)manganiferous oxides the presence of mimetite, quartz and crocoite. (unidentified). There is a large cavity partly filled with coarse-grained, crystallised cerussite, from clear to white X1972: "Carminite, Magnet, Waratah, Tasmania" in colour, with crystals up to 40 mm in size. Upon this cerussite sits one well~formed, blocky, semi~transparent to This sample contains a sprinkling of fine red needles on a smoky-brown crystal. This crystal does closely resemble brown matrix. The crystals are mostly simple hexagonal

REPORT 1993/21 prism-pinacoid combinations, and XRD indicates they are carminite, matlockite and in Tasmania must be mimetite with some minor admixed crocoite. The powdery regarded as in need of further confirmation. Searches brown matrix consists of chalcophanite, pyrolusite and through other collections and various mine dumps have goethite. failed to locate any of these species, although the right association of elements commonly exists. Phosgenite has X2161: ", Tasmania" also been confirmed at Dundas by Martin Crane (The Earth This sample contains quartz-sulphide (?chalcopyrite, etc.) Exchange, Sydney; pers. comm.). ore with a poorly crystalline yellow-green coating. XRD indicates that the coating comprises angiesite and ajarosite BIBLIOGRAPHY or -type mineral. Cuprite and antlerite also BIRCH, W. D., CHAPMAN, A.; PECOVER, S. R. 1982. The Minerals. appear to be present, but were not confirmed. The old label in: WORNER, H. K.; MITCHELL, R. w. (ed.). Minerals ofBroken appears to read: Vauquelinite, Queen of the Earth, Hill. Australian Mining and Smelting Ltd, Melbourne. Scamander River. BURR, P. S. 1992. Notes on the history of phosgenite and matlockite from Matlock, England. Mineralogical Record. X2167: "Leadhillite, Heazlewood River, 23:377-386. Tasmania" DEPARTMENT OF MINES, 1970. Catalogue of the minerals of This sample consist of a slab of coarsely crystalline galena, Tasmania. Department of Mines, Tasmania. partially oxidised. The galena is partly coated by fine-grained white cerussite, overlain by yellow-brown PETTERD, W. H. 1910. Catalogue of the minerals afTasmania. limonite, and on this limonite is growing a crust of fine to Department of Mines, Tasmania. coarse, well formed, off-white crystals. XRD indicated that the white crystals are . Some fine cerussite crystals GLOSSARY OF MINERALS also occur on the base of this specimen. Anglesite: PbS04 Antlerite: CU3(S04)(OH)4 (green) X2266: "Wulfenite, Emu River, Tasmania" Arsenolite: AS203 This sample contains fine blocky orange crystals on a white schistose matrix. It was not tested by XRD but it looks Beudantite: PbFe3(S04)(As04)(OH)6 (green) almost identical to wulfenite recorded from the Broken Hill Bindheimite: Pb2Sb206(O,OH) (yellow) Mines, NSW, an origin supported by the presence of blue Carminite: quartz and pink garnets in the matrix (Birch et ai., 1982). PbFe2(As0412(OH)2 (red) Cerussite: PbC03 X3799: ", Dundas, Tasmania" Chalcophanite: (Zn, Fe", Mn")Mn""307.3H20 This sample actually consists of three quite different Chalcopyrite: CuFeS2 specimens, and the following minerals were confirmed by XRD. Crocoite: PbCr04 (red) Cuprite: CU20 (red) Specimen A: The major part of the sample, contains Dolomite: CaMg(C03)2 powdery yellow bindheimite and minor brown goethite, both non crystalline and massive. Galena: PbS Goethite: FeO(OH) (brown) Specimen B: Contains mostly yellow to orange to green Jarosite: KFe3(S04)2(OH)6 (yellow) powdery to resinous sulphur, varying from botryoidal to dendritic to finely crystallised. Some small red sulphur Leadhillite: Pb4(S04)(C03)2(OHh globules occur, and some small clear crystals of arsenolite Litharge: PbO (red) also occur on the sample. These secondary minerals appear to overgrow a matrix rich in and chalcopyrite. Massicot: PbO (yellow) Matlockite: PbFCI Specimen C: This is a sample of partly oxidised lead ore, Mimetite: Pbs(As04)3Cl with coarse-grained galena coated by rims of white cerussite, red-orange crocoite and yellow-brown mimetite Minium: Pb304 (red) in turn. All of the secondary minerals are fine grained or Phosgenite; Pb2(C03)CI2 poorly crystallised. Pyrite: FeS2 (black-brassy) SUMMARY Pyrolusite: Mn02 (brown-black) The supposed presence of many minerals in Tasmania is Siderite: FeC03 based largely upon the identifications ofPetterd (1910). If Sphalerite: ZnS the specimens described above, originating from his collections, are truly representative, the existence of many Sulphur: S (yellow) mineral species in Tasmania must be regarded as very Vauquelinite: Pb2Cu(Cr04)(P04)(OH) (green) doubtful. Some of the above examples are Wulfenite: PbMo04 (red-yellow) mis-identifications, and some are possibly exotic samples, mis-identified as Tasmanian. From this study alone, the existence of massicot, minium, leadhillite, vauquelinite. [16 August 1993]

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