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This is an article in the field of mineral processing engineering. The adsorption kinetics of sodium oleate (SODI), sodium dodecyl sulfonate (SDS) and benzohydroxamic acid (BHA) on the surface of wulfenite were taken as the research subject.Firstly, flotation tests of pure wulfenite were conducted to study the effects of pH value and collectortype on wulfenite flotation behavior, then, the frontier orbital theory analysis and molecular dynamics simulation on adsorption behavior of these three collectors was studied by using Dmol3 module and Forcite module in Materials Studio respectively. The flotation tests resultsindicate that SODI and SDS show better collecting property than BHAin their respectiveappropriate pH range. Computational simulation study results also shows that thesethreecollectors all have strong adsorption on wulfenite {112} surface, and the molybdenumatomsonthe surface show stronger adsorption activity than other atoms due to the breakage of theoriginal Mo-O bonds, and together with the single bond oxygen atoms in polar group of collectors, arethe active particles of the adsorption process. According to the effective mass and the adsorptioninteraction energy, the adsorption ability of these there collectors could be listed as follows:SODI>SDS>BHA, which are consistent with the flotation tests.

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New data are reported on composition and morphology of wulfenite—stolzite-range minerals in oxidized ores at the Novoburannoe (Gumbeyskoe) scheelite deposit in the Southern Urals (Russia). Supergene stolzite and W-bearing wulfenite occur as veinletlike complex-zoned aggregates along the cracks in Mo-bearing scheelite at the point of contact with calcite, dolomite, chalcopyrite, and tennantite. The mineral composition varies from Mo-bearing stolzite (Pb0.98Ca0.02)(W0.78Mo0.22)О4 and W-rich wulfenite (Pb0.93Sr0.05Ca0.02)(Mo0.59W0.41)О4 to pure wulfenite. W-bearing wulfenite is predominant in the studied samples. W-free wulfenite forms pseudomorphs after molybdenite inclusions in galena. [ABSTRACT FROM AUTHOR]

Wulfenite is a useful mineral containing both lead and molybdenum. Although the Mo theoretical content of wulfenite is too low to meet the sales requirement, how to pre-concentrate the wulfenite more efficiently and economically becomes increasingly important for subsequent leaching process. Using sodium oleate (NaOL), benzohydroxamic acid (BHA) and sodium dodecyl sulfonate (SDS) as collector, the flotation behavior of wulfenite has been investigated by micro-flotation tests, and the adsorption capacity of the three collectors on wulfenite has been measured and listed as below: NaOL (pH = 9.5) > SDS (pH = 6.5) > BHA (pH = 7.5). According to the frontier orbital theory analysis, when the collector ions act on the {112} surface of wulfenite, the effective mass of NaOL is the lowest, followed by SDS and BHA. Moreover, the molecular dynamics simulation of the three collector ions on wulfenite {112} surface reveals that the two adjacent outermost molybdenum atoms of wulfenite have strong adsorption due to the fracture of the original Mo-O bonds and could easily react with the single-bond oxygen atom outside the polar groups of the three collectors. Comparing the adsorption energy, NaOL has the best adsorption performance to wulfenite {112} surface, during which the O-Mo1 distance and O-Mo2 distance are both below 2.5 Å. By associations of the simulation results with flotation tests, when the feed contains 0.14% Mo, using NaOL as collector, a rough molybdenum concentrate with molybdenum grade of 17.25% and molybdenum recovery of 86.32% has been obtained by conventional flotation tests, which provide theoretical guidance and practical evidence to promote the wulfenite flotation performance. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wulfenite is an important molybdenum oxide mineral, which has important comprehensive utilization value because of its high content of molybdenum and lead element. Based on density functional theory, first principles study on electronic properties of wulfenite crystal has been conducted, and the commonly exposed surfaces of wulfenite crystal have been predicted from the perspective of anisotropic surface broken bonds and surface energies, respectively, and the predictions have also been compared with the X-ray diffraction analysis (XRD) of pure wulfenite. The results indicate that the perfect wulfenite is of direct bandgap p-type semiconductor, and the Fermi levels are mainly contributed by the 4d5 orbital of Mo, the 2p4 orbital of O and slightly by the 6s2 orbital of Pb. the Mo --O bond has a large overlapping Mulliken population, and the electron clouds are mainly distributed along Mo -- O bonds, which indicates strong covalent bonding and hard to break. While the Pb -- O bond has a smaller Mulliken population, and no obvious electron clouds are found along Pb -- O bonds, which indicates ionic bonding or no bonding. Based on the calculations, the {112} surfaces and {001} surfaces are expected to be the most common cleavage surfaces due to their lower surface energies, smaller broken bond densities, and larger interlayer spacings than other surfaces, and the results are consistent with the X-ray diffraction (XRD) observations, which verify the accuracy of the first-principles calculation. The above conclusions will help to understand the physicochemical properties of wulfenite, and provide references for related flotation mechanism research. [ABSTRACT FROM AUTHOR]

This paper describes the formation of "sandwich" wulfenite. Banded wulfenite from the Ojuela Mine, Mapimí, Durango, Mexico, have been found since 2017, but an explanation for the band formation has not been provided. X-ray diffraction (XRD) showed the wulfenite to have a tetragonal unit cell of a = 5.4374(1), c = 12.1123(7) Å. The Raman spectrum was dominated by ν1 (Ag) around 870 cm-1, while the weak shoulder at 859 cm-1 represents the strain activated ν1 (Bu) infrared (IR) band. Two ν2 modes were observed at 318 cm-1 (Ag) and 351 cm-1 (Bg). For the ν3(Eg), the band at 768 cm-1 was assigned to the Bg symmetric mode and the 745 cm-1 band to the Eg vibration. The IR spectrum showed two strong bands at 835 and 779 cm-1 corresponding to v3 modes and a very weak one at 496 cm-1. SEM-EDX (scanning electron microscopy - energy dispersive X-ray analysis) showed that the band does not extend into the main crystal but is limited to the surface as secondary growth. The main thick tabular crystal was dominated by {001}, {110}, and {111}. The {001} surfaces of the wulfenite crystals showed evidence of later dissolution, which may have been part of the source material for this secondary crystallization. The chemical composition of the main wulfenite crystal proved only minor substitution of W for Mo. Contrastingly, a much higher number of substitutions by V, As, and W for Mo - as well as Ca, Fe, Zn, Cu, and Al for Pb - was observed in the secondary band, indicating a change in the fluid composition from which the band crystallized compared to the original wulfenite. Changes in lattice parameters of the secondary wulfenite crystals and the energy involved in nucleation on the surface of the original wulfenite as well as the different bonds exposed on different faces favored the formation of the band on only {110}. [ABSTRACT FROM AUTHOR]

Natural wulfenite is lead molybdate (PbMoO4), which has extensive and vital economical values based on its rarity and molybdenum extraction. Through the density functional theory calculation, the electronic structure and bond population were first investigated, and the predominantly exposed surfaces were predicted. Based on the calculations, the {1 1 2} and {0 0 1} surfaces are expected to be the most common cleavage surfaces due to their lower surface energies, smaller broken bond densities, and larger interlayer spacings than other surfaces; and the results are consistent with the X-ray diffraction (XRD) observations. Moreover, the {1 1 2} and {0 0 1} cleavage surfaces were intuitively observed by atomic force microscopy (AFM), and {1 1 2} cleavage surfaces are rather smooth and flat, while the {0 0 1} cleavage surface have separated terrace, indicating that the cleavages occur more easily along {1 1 2} surfaces than along {0 0 1} surfaces. The above conclusions in this paper have important theoretical significance and guidance on in-deep understanding of the wulfenite leaching and flotation mechanisms.

Copyright of Hydrometallurgy of China is the property of Hydrometallurgy of China Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Bio-induced precipitation of lead-bearing minerals is investigated in bacterial biofilms grown by Shewanella oneidensis MR-1 under aerobic conditions. Under the different conditions investigated, thermodynamic calculations establish that the stable mineral phases expected to precipitate are either wulfenite PbMoO 4 or cerussite PbCO 3. However, observations by electron microscopy show that the first solids precipitated within hours at the experimental solution/biofilm interface are crystals of about 20 nm in diameter of pyromorphite Pb 5 (PO 4) 3 (OH,Cl). In Mo-bearing systems, the precipitation of the thermodynamically-predicted wulfenite phase is delayed compared to the abiotic experiment and is observed only after seven days of lead exposure. The initial lead phosphate crystals observed on the extracellular polymeric substances are assumed to result from concurrent local abundances of adsorbed Pb2+ ions and phosphate groups released by metabolically active cells. Scanning electron microscopy observations of samples milled by focused ion beam reveal effective diffusion-limited precipitation of pyromorphite within the well-preserved biofilm porosity. Graphical abstract Unlabelled Image Highlights • Biofilm activity drives pyromorphite (Pb 5 (PO 4) 3 Cl) precipitation. • The thermodynamically-stable wulfenite formation is delayed in biofilm. • Focused ion beam milled sections of the biofilm reveal gradients in lead biomineralization. [ABSTRACT FROM AUTHOR]

The article focuses on the characteristics and qualities of wulfenite found in different localities of Mexico. Overview of the different localities of the region which have produced several quantities of great specimens with distinctive beauty and abundance is offered. The history of different mines in various localities in the country are also mentioned.

The article focuses on the qualities and characteristics of wulfenite found in Arizona. Topics include the approval of the state's legislature and governor for wulfenite as the official state mineral to join copper, the list of best-of-species found in different localities of the state, and the recognized qualities and characteristics of the rock.

The article features classical scientist Franz Xaver Freiherr von Wulfen, who discovered and described then-unknown plants, mushrooms, and lichens as well as animals and minerals. Breif overview of Wulfen's personal and educational background, and his focus in three realms of nature such as plants, animals and minerals, is offered. The scientists who have influenced Wulfen's works and his pioneering works in naming several wulfenite specimen are also mentioned.

The article focuses on the different wulfenite stamp collections. It mentions philatelic organization American Topical Association (ATA) whose members collect postage stamps of gemstones and minerals from different countries. It also features various postage stamps with unique and distinct pictures of mineral wulfenite.

The article focuses on the qualities and characteristics of wulfenites from Tsumeb, Namibia. Discussion of the history of the first discovery of wulfenites through different mines in the area that lead to the growth of collections in various museums is offered. Description of the different specimens, crystallography, habit and color of wulfenites that were produced in the area is also mentioned.

The article focuses on the different wulfenite localities in New Mexico. Overview of the different mines in the region and the prevalence of wulfenite in the Bennett orebody which have inspired various collectors who were familiar in the area is offered. Information on the geology of wulfenite formation in the area and the history of the collection of the mineral is also mentioned.

The article focuses on the history of wulfenite and its subsequent refinement into several categories or varieties of pseudomorphs in Namibia. Brief overview of the meaning and definition of pseudomorph, which has outward form proper to another species of mineral, is offered. The other categories or varieties of pseudomorphs that have entered the literature with recognized terms are also mentioned.

Abstract Laboratory batch experiments were conducted to study Mo isotope fractionation during the precipitation of powellite (CaMoO 4) and wulfenite (PbMoO 4). These minerals act as important sinks of dissolved Mo, especially in alkaline-pH mine drainage. Their precipitation might be traceable through Mo isotope analyses, provided that it induces Mo isotope fractionation. Experiments involved the presence/absence of dissolved sulfate and inorganic carbon (DIC) to better mimic the aqueous chemistry of mine drainage, as these constituents are characteristic of mine waters. Molybdate minerals preferentially incorporated light Mo isotopes from aqueous solution with fractionation patterns that are linked to the saturation state. The Rayleigh fractionation model was most suitable to describe powellite precipitation under supersaturated conditions. The average Rayleigh isotope separation factor for powellite precipitation was −0.82 ± 0.12‰, with no significant effect from the presence/absence of sulfate and DIC. Upon approaching chemical equilibrium, bidirectional exchange of molybdate between dissolved Mo and powellite led to a pronounced release of isotopically light Mo to solution, which overrode the Rayleigh fractionation pattern formed at early time. Molybdenum isotope data during wulfenite precipitation could reasonably be fitted using the Rayleigh and equilibrium fractionation models, which yielded isotope separation factors of −0.25 ± 0.10‰ and −0.75 ± 0.07‰, respectively. These results contribute to a growing knowledge of Mo isotope fractionation during processes of dissolved Mo removal (e.g., adsorption and precipitation), thus far all of which show that an enrichment in heavy Mo isotopes in solution is indicative of Mo attenuation. [ABSTRACT FROM AUTHOR]

Abstract Superposition model (SPM) analysis is employed for determination of the crystal field parameters (CFPs) for Co2+ ions doped into PbMoO 4 crystal. SPM calculations utilize structural data to model parameters spectroscopically measured for the dopant ions. The CFPs predicted by SPM assuming axial site symmetry serve as input for the CFA/MSH package, which incorporates the CF analysis (CFA) and the microscopic spin Hamiltonian (MSH) modules. This approach enables modeling of the optical energy levels as well as the axial SH parameters: zero-field splitting parameter (ZFSP) D and g i factors: g || and g ⊥. The theoretical SH parameters are matched with the ones deduced from experimental electron magnetic resonance (EMR; EPR) data for Co2+(3 d7) ion using projection of g i for the effective spin S ˜ = 3 2 onto g i ' for the fictitious spin S ' = 1 2. Various structural models are considered to predict the CFPs and thus ZFSPs. The local distortion polar angles Δθ in the vicinity Co2+ ions in PbMoO 4 are obtained for tetrahedral (Mo6+) and dodecahedral (Pb2+) sites for two possible structural configurations, thus confirming the structural distortions induced by Co2+ doping. This enables discerning between Co2+ ions located at the Pb2+ sites and those at the Mo6+ sites. The experimental data available for one type of the two observed Co2+ complexes in PbMoO 4 are reanalyzed. Highlights • Electron magnetic resonance (EMR). • Optical spectroscopy. • Zero-field splitting (ZFS). • Crystal field (CF). • Co2+ ions in PbMoO4. [ABSTRACT FROM AUTHOR]

Pigments appearing on ninth-twelfth-century AD-carved stucco, wall painting, and terracotta friezes excavated at Nishapur in north-eastern Iran were investigated by optical reflectance spectroscopy, micro X-ray fluorescence spectrometry (μ-XRF), X-ray diffractometry (XRD), micro-Raman spectroscopy (μ-Raman), and scanning electron microscopy (SEM). Many of the pigments identified including vermilion, red lead, hematite, limonite, carbon black, atacamite, calcite, and gypsum have been identified in previous studies of pigments used in later Islamic periods. However, a series of unusual pigments such as wulfenite, pyromorphite, phoenicochroite, and jarosite were also found in the present study. The association of kaolinite and alunite with limonite and other Fe-bearing yellow pigments points to a local provenance for these pigments. In addition, the presence of orpiment in the vermilion may be indicative that the vermilion was artificially manufactured. These findings suggest that pigment use and manufacturing during the ninth to eleventh centuries in Nishapur was still in a trial-and-error stage and the palette known from the twelfth century onwards had not yet been systematized. [ABSTRACT FROM AUTHOR]

The article offers information on minerals that are reported in central Iran such as that of fluorite, andradite, wulfenite, mimetite and vanadinite. Topics discussed include information on Iranian zeolites that are found in northwestern Iran; information on trapezohedral crystals of analcime which were found during construction of a tunnel going through Mount Kahovan, Iran; and information on the Qaragol or Gharah Gol Boron mine located in Zanjan Province, Iran.

This paper reports the results of studies performed on a painted stucco fragment excavated at the Ghaleh Guri in Ramavand, western Iran, and dated back to the late Sasanian period (224–651 AD). Analytical studies including micro-Raman spectroscopy (μ-Raman), micro-X-ray spectrometry (μ-XRF) and optical microscopy showed that red lead and vermilion were used as main pigments on this fragment. Moreover, carbon black was diagnosed to thinly cover some parts of the red lead. Peculiarly, wulfenite (PbMoO 4 ) associated with vanadinite (Pb 5 (VO 4 ) 3 Cl) was identified to compose a yellow stain sporadically dispersed on the other pigments. [ABSTRACT FROM AUTHOR]

An unusually rich occurrence of supergene minerals, represented by azurite, baryte, cerussite, Zn-rich malachite, rosasite, smithsonite and wulfenite was recently identified at the subsurface parts of the Nová Anton epithermal ore vein near Hodruša-Hámre, Štiavnické vrchy Mts., Slovak Republic. Azurite is rare and it forms bright blue crystalline crusts, which consists of thin tabular crystals up to 2 mm. It is associated together with malachite, cerussite and smithsonite. Baryte occurs only infrequently as white, thin tabular crystals up to 5 mm growing on smithsonite. Cerussite is relatively abundant supergene mineral, especially in the proximity of relicts of primary galena. It forms clear to white, well-developed, acicular, prismatic or tabular crystals up to 1.2 cm or massive aggregates and rims up to 3 cm, which are often associated together with malachite and rosasite. Zn-rich malachite is very common supergene mineral at the studied locality and it occurs as pale green to greenish-blue hemispherical or radial aggregates up to 1 cm or crystalline crusts and coatings, which cover areas up to 100 cm². It is often associated with cerusite or smithsonite with rosasite, rarely also together with wulfenite or azurite. The unit-cell parameters of Zn-rich malachite refined from the powder X-ray diffraction data (for the monoclinic space group P21/a) are: a = 9.459(5) Å, b = 11.979(4) Å, c = 3.219(1) Å, β = 97.84(with)° 2 V = 361.3(3) Å3. It contain up to 0.18 apfu of Zn. Rosasite is relatively common species. It forms bluish-green to pale blue, hemispherical aggregates up to 7 mm with radial internal structure, which are often grouped to the botryoidal crusts covering areas up to 50 cm². Rosasite is often associated with smithsonite and Zn-rich malachite. Its refined unit-cell parameters (for the monoclinic space group P21/a) are: a = 12.890(8) Å, b = 9.342(7) Å, c = 3.164(2) Å, β = 110.26(2)° with V = 357.4(4) ų. Two types of rosasite can by distinguished by chemical composition. Predominant is Zn-rich phase with the Cu/Zn molar ratio in the range of 1.24 - 1.66 (1.11 - 1.25 apfu Cu, 0.75 - 0.89 apfu Zn). Cu-rich rosasite is infrequent and its Cu/Zn molar ratio vary from 3.32 to 3.61 (1.54 - 1.57 apfu Cu, 0.43 - 0.46 apfu Zn). Smithsonite is very common mineral, which is associated mainly with Zn-rich malachite and rosasite. It occurs as white, pale green to pale blue botryoidal crusts, which often consists of rounded rhombohedral or scalenohedral crystals up to 3 mm in size. Except of major Zn, elevated content of Cu (up to 0.08 apfu), and minor contents of Ca (up to 0.02 apfu) and K, Pb, Mg (all up to 0.01 apfu) were detected in smithsonite. Wulfenite is relatively abundant species and it forms orange to yellow, dipyramidal, often hemihedral or tabular crystals up to 1 cm. It was identified by PXRD and its refined unit-cell parameters (for the tetragonal space group I41/a) are: a = 5.438(5) Å, c = 12.1160(7) Å and V = 358.3(3) ų. Its chemical composition is close to the theoretical end member, PbMoO4. Well-developed supergene zones in-situ, especially with the abudance of supergene Cu and Zn carbonates are not typical for the epithermal ore veins in the Banská Štiavnica ore district. The origin of relatively well developed and rich supergene zone in-situ at the Nová Anton vein is directly linked with the fact, that upper parts of this vein are hosted in limestone. [ABSTRACT FROM AUTHOR]

[Display omitted] • Successful sulphidisation took place on wulfenite surface. • On wulfenite surface, lead ions reacted with sulphide ions to form lead sulphide. • Lead molybdate also reacted with sulphide ions to form lead sulphide. • Successful sulphidisation did not take place on powellite surface. • On powellite surface, calcium hydromolybdate transitioned into calcium molybdate. With the increasing demand for molybdenum, low-grade molybdate (Metal-MoO 4) reserves have to be processed. However, the surfaces of molybdate minerals do not respond well to flotation in the mineral enrichment process. This study aimed to understand whether the surfaces of molybdate minerals could be sulphidised to form a new metal sulphide phase which has a good flotation response. The sulphidisation was conducted on the surfaces of powellite (CaMoO 4) and wulfenite (PbMoO 4), the two most common molybdate minerals and the sulphidised surfaces were investigated by Scanning Electrochemical Microscopy and Cryogenic X-ray Photoelectron Spectroscopy. It was found that successful sulphidisation took place on the surface of wulfenite and the major sulphidisation reaction involved the reaction of lead ions originating from lead hydromolybdate with sulphide ions to form a new lead sulphide layer. However, effective sulphidisation did not take place on the surface of powellite without the formation of a new metal sulphide phase, but the addition of the sulphidiser promoted the transition of calcium hydromolybdate to calcium molybdate. [ABSTRACT FROM AUTHOR]

The article offers information on the stottite crystals which is discovered in Tsumeb, Namibia in 1957 by miner Friedrich Gramatzki. It says that the stottite crystals become the first naturally occurring germanate around the world and named to honor Charles E. Stott, the general manager of Tsumeb Corp. Ltd. It mentions the importance of analytical verification to correctly identify stottite against siderite and dipyramidal wulfenite.

The article provides an overview of the mineral collecting localities in Iran and the mineralogical descriptions and observations of some of mineral specimens like wulfenite. Topics include the occurrence of lead-zinc (Zn-Pb) ore deposits in Iranian metallogenic belts, the discovery of Iranian wulfenites at Chah-Kharboze mine, and the wulfenite crystals at Ahmad Abad mine.

An interesting association of supergene minerals represented by anglesite, aragonite, brianyoungite, cerussite, gypsum, hemimorphite, malachite, mimetite, pyromorphite and wulfenite was found at the Čavoj base metal deposit, Strážovské vrchy Mts., Slovak Republic. Brianyoungite occurs as white crystalline coatings and irregular to spherical aggregates, which consist of thin-tabular crystals up to 0.1 mm in size. It was found together with aragonite and gypsum on the surface of ore fragments at the dumps of Geschenk and Ferdinand shaft. The refined unit-cell parameters of brianyoungite from the powder X-ray data are: a 15.710(8) Å, b 6.273(7) Å, c 5.45(1) Å, V = 537(1) Å3. Cerussite is the most abundant supergene phase. It forms well developed colourless to white tabular or prismatic crystals up to 5 mm in size, associated together with anglesite, mimetite, pyromorphite and wulfenite. Its refined unit-cell parameters are: a 5.189(1) Å, b 8.507(2) Å, c 6.152(1) Å, V 271.56(9) Å3. Hemimorphite was identified at the dumps situated near Strieborná adit as white hemispherical crystalline aggregates up to 2 mm in the fissures of sphalerite-rich gangue. It is orthorhombic, space group Imm2 and the unit-cell parameters refined from X-ray powder diffraction data are: a 8.3634(8) Å, b 10.711(1) Å, c 5.1134(5) Å, and V 458.07(8) Å3. Mimetite is rare mineral and it occurs only at the Baniská area. It forms bright yellow to yellowish-green crystalline aggregates and crusts, which are composed by prismatic crystals up to 1 mm in size. Its unit-cell parameters refined from powder X-ray data are: a 10.236(10) Å, c 7.4126(9) Å and V 673(1) Å3. Mimetite from the Čavoj deposit contain only minor amounts of Ca (up to 0.33 apfu) and P (up to 0.39 apfu) with the empirical formula (average of 6 point analyses) corresponding to (Pb5.11Ca0.21)Σ5.32 [(AsO4) 2.77 (PO4) 0.23]Σ3.00Cl1.17 on the basis of P+As+V+Si+S=3 apfu. Pyromorphite was identified in several samples from the Ferdinand shaft dump as pale-green to pale-yellow prismatic crystals up to 2 mm in size, which are often grouped to the crystalline crusts and aggregates together with cerussite and wulfenite. The refined unit-cell parameters of pyromorphite are: a 9.986(8) Å, c 7.3528(3) Å and V 635.0(5) Å3. Only minor amounts of Ca (up to 0.19 apfu) and As (0.07 apfu) were detected in studied samples of pyromorphite and its empirical formula (average of 9 point analyses) is corresponding to (Pb4.97Ca0.10)Σ5.07 [(PO4) 2.95 (AsO4) 0.05]Σ3.00Cl1.15 on the basis of P+As+V+Si+S=3 apfu. Wulfenite is rare supergene phase at the studied locality (dump of Ferdinand shaft) and it occurs as well developed, orange pyramidal crystals up to 1 mm in size together with cerussite and pyromorphite. It is tetragonal, space group I41/a and its unit-cell parameters refined from X-ray powder diffraction data are: a 5.435(1) Å, c 12.1065(2) Å and V 357.59(9) Å3. Its chemical composition is close to the end member formula with only insignificant amounts of P and As (both up to 0.01 apfu) and empirical formula (average of 5 point analyses) corresponding to Pb1.00 [(MoO4) 0.98 (AsO4) 0.01 (PO4) 0.01]Σ1.00 on the basis of Mo+W+As+P=1 apfu. On the basis of detailed paragenetic study two principal associations of supergene minerals were distinguished at the Čavoj deposit: a) supergene phases (e.g. cerussite, hemimorphite, mimetite, pyromorphite or wulfenite) formed by in-situ decomposition of primary ore minerals in the supergene zone or b) supergene minerals of sub-recent origin, which were formed by the weathering of ore fragments in dump environment (e.g. aragonite, brianyoungite and gypsum). [ABSTRACT FROM AUTHOR]