Explore the vast range of titles available.

The Silver King mine (also known as Forsyths) operated very intermittently between about 1911 and the late 1940s on Livingstone Creek, near Omeo, in northeastern Victoria. The deposit consists of six thin and discontinuous quartz lodes that are variably mineralised. Assays of up to 410 ounces of silver per ton were obtained but there are only a few recorded production figures. Examination of representative ore samples shows that the main silver-bearing minerals in the primary ore are pyrargyrite, freibergite, andorite and the rare sulphosalt zoubekite, which occur irregularly with pyrite, arsenopyrite, galena and sphalerite. Phase assemblage data indicate that crystallisation occurred over an interval from about 450°C to less than 250°C, with the silver-bearing minerals crystallising at the lowest temperatures. The lodes were formed by the emplacement of hydrothermal solutions into fractures within the Ensay Shear Zone during the Early Devonian Bindian Orogeny. There are similarities in mineralisation and timing of emplacement between the Silver King lodes and the quartz-reef-hosted Glen Wills and Sunnyside goldfields 35-40 km north of Omeo.

Au-Hg-Ag phases have been described from a variety of metallogenic orebodies and the placer deposits derived from them. In many documented placer deposits, the phases typically occur intergrown as 'secondary' rims to primary Au-Ag grains. The origin of these rims has been ascribed to supergene redistribution reactions during deposition or to the effects of amalgamation (i.e. use of mercury) during mining for gold. Difficulties in determining compositions and crystal structures on such a small scale have made full characterisation of these phases problematic. This paper describes a new occurrence of these phases, found by accident during investigation of a historical concentrate of 'osmiridium' containing a number of gold grains from beach sands at Waratah Bay, in southern Victoria, Australia. The phases occur as rims to gold grains and are intergrown on a scale of tens of micrometres or less. Application of electron microprobe analysis (EPMA) and limited electron back-scattered diffraction (EBSD) was required to characterise them. These techniques revealed the presence of the approved mineral weishanite (Au-Hg-Ag) and a phase with compositional range Au2Hg-Au3Hg surrounding primary Au-Ag (electrum) containing trace amounts of Hg. EBSD analysis showed weishanite is hexagonal P63/mmc and Au2Hg to be hexagonal P63/mcm. Comparison with published data from other localities (Philippines, British Columbia and New Zealand) suggests weishanite has a wide compositional field. Textures shown by these phases are difficult to interpret, as they might form by either supergene processes or by reaction with anthropogenic mercury used during mining. However, in the absence of any historical evidence for the use of mercury for gold mining at Waratah Bay, we consider the formation of the Au-Hg phases is most probably due to supergene alteration of primary Au-Ag alloy containing small amounts of Hg. In addition to revealing some of the reaction sequences in the development of these secondary Au-Hg-Ag rims, this paper illustrates methods by which these phases can be more fully characterised and thereby better correlated with the Au-Hg synthetic system.

The Maryborough meteorite is a new H5 ordinary chondrite discovered about 2 km south of Maryborough, Victoria, in May 2015. It is a single stone measuring approximately 39 × 14 × 14 cm and with a mass of 17 kg. Plentiful indistinct chondrules are up to 1 mm across in a strongly recrystallised plagioclase-bearing matrix. Olivine and orthopyroxene in both the matrix and chondrules are uniform in composition (Fo80.1Fa19.3Te0.5Ca-ol0.04 and En81.5Fs17.1Wo1.5 respectively).The main metallic phases present are kamacite, taenite and tetrataenite, often forming composite grains with troilite. There is no evidence for any shock-inducing event and the meteorite shows incipient weathering in the form of thin iron-oxide mantles around the Fe–Ni grains. A terrestrial age of less than 1000 years is estimated from C14 dating. While there are a number of historic reported meteor sightings in the Maryborough district, none can be tied to the meteorite’s find site. To date, Maryborough is the third H5 ordinary chondrite and the second largest single chondritic mass, after Kulnine (55 kg), found in Victoria.

Tin- and tantalum-bearing LCT-type granitic pegmatites occur in a 45 km long belt between Eskdale and Mount Wills in north-eastern Victoria. Near Mount Wills, several compositionally zoned rare-element pegmatites contain complex assemblages of primary and secondary phosphate minerals, many of which are rare and previously unrecorded in Victoria. The phosphate assemblages can be divided into Al-rich and Fe–Mn-rich suites, in addition to ubiquitous fluorapatite. The Al-rich phosphate suite includes montebrasite, scorzalite, bertossaite and brazilianite. The Fe-Mn phosphate suite includes heterosite, phosphoferrite, wolfeite, alluaudite (sp.), arrojadite (sp.) and jahnsite (sp.), derived from the metasomatic alteration of primary triplite. Further hydrothermal alteration of this assemblage has resulted in a secondary suite of strengite, rockbridgeite, phosphosiderite, whiteite, jahnsite and whitmoreite forming in etch cavities and fractures. A Late Silurian age of 420±4 Ma was obtained from one of the dykes via CHIME radiometric dating of monazite, suggesting a similar age for the adjacent Mount Wills Granite, which has not been reliably dated. This highly fractionated, peraluminous granite is presumed to be the source of the rare-element pegmatites based on their close spatial relationship.

The Wombat Hole Prospect is a small copper–bismuth–(tellurium) exoskarn cropping out in the Morass Creek gorge, near Benambra, in eastern Victoria, Australia. Its main primary sulfide constituent is bornite in a grossular‒vesuvianite matrix. The skarn formed in a megaclast of Lower Silurian limestone from metal-bearing fluids accompanying the high-level emplacement of the Late Silurian–Lower Devonian Silver Flat Porphyry. Though the primary bornite mineralisation has been nearly obliterated by weathering, there are small relict patches containing exsolved grains of wittichenite (Cu 3 BiS 3 ) and chalcopyrite, as well as inclusions of bismuth tellurides in the tetradymite group, namely sulphotsumoite (Bi 3 Te 2 S) and hedleyite (Bi 7 Te 3 ). Joséite-A (Bi 4 TeS 2 ), a mineral with a formula Bi 3 (Te,S) 4 , several unnamed Cu–Bi‒Te phases and minute grains of native bismuth have also been detected. Pervasive veining by chrysocolla throughout the garnet‒vesuvianite host contains a range of unusual secondary bismuth minerals that have crystallised at various times. These include mrázekite, namibite, pucherite, schumacherite and eulytine. Other secondary minerals present include wulfenite, bismutite, azurite, malachite and a poorly-crystalline bismuth oxide containing several weight percent tellurium. Rare grains of gold (electrum) containing up to 23 wt.% Ag are also present. The assemblage of grossular–vesuvianite with minor diopside is indicative of formation in a low-${\\rm X}_{{\\rm C}{\\rm O}_ 2}$environment under fluid-buffered conditions. A temperature range between ~650°C and as low as ~150°C can be estimated from the exsolution of wittichenite and chalcopyrite from the bornite. The tetradymite-group inclusions formed first under low values of$f_{{\\rm S}_ 2}$/$f_{{\\rm T}{\\rm e}_ 2}$, with bornite crystallising as values increased. The primary Cu‒Bi‒Te mineralogy and the unusual secondary mineral assemblage makes the Wombat Hole skarn unique in southeastern Australia. The deposit provides scope for studying the mobility of elements such as Bi and Te over short distances during weathering of hypogene ore minerals.

The Wedderburn meteorite from Victoria is a small nickel-rich iron belonging to the rare sLH subgroup of the IAB complex. Donated to the Mines Department in 1950, it came to public attention in 1953 when the initial description was published by Dr Austin Edwards in the Proceedings of the Royal Society of Victoria . Since then, pieces of the meteorite have been distributed to major institutions in Europe and North America, where leading researchers have investigated the meteorite’s unusual chemistry, mineralogy and microtexture in great detail. The recent approval of a new iron carbide mineral named edscottite, with the formula Fe5C2, in Wedderburn has prompted this review of the meteorite’s history, from its discovery to its current classification status.

Wortupaite (IMA2022-107) is a new hydrated magnesium nickel tellurite mineral with a zemannite-like structure, described from the Wortupa gold mine, South Australia, Australia. Wortupaite forms needles up to 25 µm in length, generally clustered and sometimes in blocky masses of shorter (10-15 µm) crystals. Wortupaite is found growing on melonite, from which the component nickel and tellurium are derived, and is associated with calcite. The strongest powder diffraction lines are [dobsÅ(Iobs)(hkl)]: 8.059 (93) (100), 4.034 (92) (200), 2.832 (43) (211 and 121), 2.769 (100) (202) and 1.920 (45) (213 and 123). The empirical formula of wortupaite as determined by electron probe microanalysis is (Mg0.57Ni0.39Mn0.04)Σ1(Ni2+1.87Fe3+0.13)Σ2(Te4+O3)3·3H2O , simplified to the ideal formula of MgNi2+2(Te4+O3)3·3H2O with H2O content calculated from the crystal structure. The average crystal structure of wortupaite was determined by single-crystal X-ray diffraction with synchrotron radiation (R1 = 0.0558 for 100 independent reflections). Wortupaite is hexagonal, crystallising in the space group P63/m, with a = 9.2215(13) Å, c = 7.5150(15) Å, V = 553.43(19) Å3 and Z = 2. Wortupaite has a microporous structure, with the negatively charged zemannite-like framework formed by Te4+O3 trigonal pyramids and Ni2+O6 octahedra. For charge balance, Mg2+ and Ni2+ dominant sites are assumed to be located on central sites in the channels, coordinated by 6 H2O groups. An OW site was refined around the Mg2+ dominant site, but OW position(s) were not locatable around the Ni2+ dominant site. A discussion of the different models for crystallographic arrangement of channel species is provided, taking into account possible Fourier truncation effects. Unlike the other four minerals with zemannite-like structures which have a near 50% split of divalent and trivalent framework cations, wortupaite is the first natural phase to have only divalent cations in the framework sites.

The new mineral gobelinite, ideally CoCu4(SO4)2(OH)6⚫6H2O, is a new member of the ktenasite group and the Co analogue of ktenasite, ZnCu4(SO4)2(OH)6⚫6H2O. It occurs at Cap Garonne (CG), Var, France (type locality), and Eisenzecher Zug (EZ), Siegerland, North Rhine-Westphalia, Germany (cotype locality). The mineral forms pale green, bluish green or greyish green, blocky to thin, lath-like crystals. They are transparent and non-fluorescent, with a vitreous, sometimes also pearly, lustre and a white streak having a pale-green cast. Mohs hardness is about 2.5. The crystals are brittle with an irregular fracture; no cleavage was observed. D(meas.) is 2.95(2) and D(calc.) is 2.907 g cm−3 (for empirical formula, CG). Common associates are brochantite and various other hydrated metal sulfates. Electron-microprobe analyses of the CG material yielded (wt. %) CuO 42.45, CoO 6.58, NiO 3.37, ZnO 3.14, SO3 22.12, and H2O 22.62 (calculated on structural grounds), and total = 100.30 wt. %, giving the empirical formula (based on 20 O atoms) (Co0.63Ni0.32Zn0.28Cu3.83)Σ5.06S1.98O20H18.00. The simplified formula is (Co,Ni)(Cu,Zn)4(SO4)2(OH)6⚫6H2O, and the endmember formula is CoCu4(SO4)2(OH)6⚫6H2O. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDS) analyses of the (Zn-free) EZ material gave the simplified average formula (Co0.92Ni0.21Mg0.01Cu3.79)Σ4.93(SO4)2.08(OH)6⚫6H2O. Optically, gobelinite (CG) is biaxial negative, with α=1.576(2), β=1.617(2) and γ=1.630(2); 2Vmeas=58(4)∘ and 2Vcalc=57.5∘. Dispersion is weak, r>v; orientation is X=β, Y=γ and Z≈α, with strong pleochroism X equaling colourless, Y equaling green and Z equaling pale green. The mineral is monoclinic, space group P21∕c, with a=5.599(1), b=6.084(1), c=23.676(5) Å, β=95.22(3)∘ and V=803.2(3) Å3 (at 100 K; CG) and a=5.611(1), b=6.103(1), c=23.808(5) Å, β=95.18(3)∘ and V=811.9(3) Å3 (at 298 K; EZ), respectively (Z=2). The eight strongest measured powder X-ray diffraction lines (d in Å (I) hkl (CG material)) are 11.870 (100) 002, 5.924 (40) 004, 4.883 (10) 102, 4.825 (15) 013, 3.946 (15) 006, 2.956 (15) 008, 2.663 (20) 202 and 2.561 (15) 1‾23. Single-crystal structure determinations gave R1=0.0310 (CG) and 0.0280 (EZ). The atomic arrangement is based on brucite-like sheets formed from edge-sharing, Jahn–Teller-distorted (4+2 coordination) CuO6 octahedra. These sheets are decorated on both sides with SO4 tetrahedra and linked via hydrogen bonds to interstitial, fairly regular Co(H2O)6 octahedra. The name alludes to the Old French word gobelin, equivalent to the German word kobold, from which the designation of the element cobalt was derived.

Utahite was first described in 1997 based mainly on powder X-ray diffraction data and electron microprobe data. No crystal structure was reported. The re-examination of utahite using single-crystal X-ray diffraction and electron microprobe analysis has shown that utahite contains essential Mg, along with Cu, Zn, Te, O and H. The missing MgO was originally attributed to additional H2O. The redefinition of utahite to MgCu2+4Zn2Te6+3O14(OH)4·6H2O from Cu2+5Zn3(Te6+O4)4(OH)8·7H2O has been accepted by the IMA–CNMNC, Proposal 20-C. Utahite is triclinic, crystallising in P1¯ with the unit-cell parameters a = 5.6831(4) Å, b = 8.7793(6) Å, c = 9.9818(9) Å, α = 95.415(7)°, β = 104.129(7)°, γ = 90.098(6)° and V = 480.65(7) Å3, in good agreement with the original study. Utahite features a new framework arrangement of Cuφ6 octahedra, Znφ4 tetrahedra and Teφ6 octahedra (where φ = O or OH), with Mg(H2O)6 octahedra occupying the channel space. Two-thirds of the Te sites form Te6 + 2O10 dimers and one third form [Te6+O4(OH)2]4− octahedra, spatially separated from other Te6+ sites. Although unique, the structural framework of utahite is similar to that of leisingite, with both minerals having layers composed of Cuφ6 and Teφ6 octahedra with Mg(H2O)6 octahedra in the interlayer space; however leisingite does not contain Zn. New Raman spectroscopic data is also reported for utahite.