The system Pd–Ag–S: phase relations and mineral assemblages

2020 ◽  
Vol 84 (1) ◽  
pp. 125-130
Author(s):  
Anna Vymazalová ◽  
František Laufek ◽  
Alexandr V. Kristavchuk ◽  
Dmitriy A. Chareev
Keyword(s):  
Mineral Assemblage ◽  
Glass Tube ◽  
S Phase ◽  
Mineral Deposits ◽  
Mineral Assemblages ◽  
Pd Alloy ◽  
Stable Association ◽  
Silver Palladium ◽  
New Phase ◽  
Silica Glass Tube

AbstractPhase equilibria in the system Pd–Ag–S were studied using the silica-glass tube method at 400°C and 550°C. In the system we synthesised three ternary phases: coldwellite (Pd3Ag2S), kravtsovite (PdAg2S) and a new phase Pd13Ag3S4. At 400°С, coldwellite forms a stable association with vysotskite (PdS) and vasilite (Pd16S7); vysotskite and kravtsovite; phase Pd4S and a Ag–Pd alloy; it also coexists with a new phase Pd13Ag3S4. Kravtsovite is stable up to 507°C; the presence of kravtsovite in the mineral assemblage reflects its formation below this temperature. The occurrence of coldwellite, vysotskite and Ag2S together in equilibrium reflects the formation of this mineral assemblage above this temperature (507°C). Coldwellite is stable up at 940°С. Mineral assemblages defined in this study can be expected in Cu–Ni–PGE mineral deposits, associated with mafic and ultramafic igneous rocks, in particular in mineralisations with known silver–palladium sulfides.

The system Ag–Pd–Te: phase relations and mineral assemblages

2015 ◽  
Vol 79 (7) ◽  
pp. 1813-1832 ◽  
Author(s):  
Anna Vymazalová ◽  
František Laufek ◽  
Alexandr V. Kristavchuk ◽  
Dmitriy A. Chareev ◽  
Milan Drábek
Keyword(s):  
Glass Tube ◽  
Phase Relations ◽  
Mineral Deposits ◽  
New Mineral ◽  
Temperature Phase ◽  
Compositional Range ◽  
Platinum Group Minerals ◽  
Mineral Assemblages ◽  
Stable Association ◽  
Silver Palladium

AbstractThe phase equilibria in the system Ag–Pd–Te were studied by the technique of using an evacuated silica glass tube at 350° and 450°C. Five ternary phases were synthesized: sopcheite (Pd3Ag4Te4), lukkulaisvaaraite (Pd14Ag2Te9),telargpalite (Pd2–xAg1+xTe) and the previously unknown phases Pd7.5–xAg0.5+ xTe3 and Pd2+xAg2–xTe.The synthetic telargpalite has a compositional range from 26 to 29 wt.% Ag, with the formula Pd2–xAg1+xTe, where x varies from 0.09 to 0.22. The phase Pd2+xAg2–xTe has a compositional range from 34 to 35 wt.% Ag, where x varies from 0.18 to 0.24. The phase Pd7.5–xAg0.5+xTe3 forms a solid solution from 4 to 11 wt.% Ag, where x varies from 0.02 to 0.83. Phases Pd20Te7and Pd13Te3 dissolve up to 3.5 and 2 wt.% Ag, respectively. Other binary palladium tellurides do not dissolve Ag. The phase Pd3Ag4Te4, an analogue of the mineral sopcheite, forms a stable association with hessite and kotulskite it also coexists with lukkulaisvaaraite. Sopcheite is stable up to 383°C. Natural occurrences of hessite, kotulskite and lukkulaisvaaraite together in equilibrium indicate formation above this temperature. Phase relations defined the mineral assemblages that can be expected to occur in nature.The phase Pd7.5–xAg0.5+xTe3 potentially represents a new mineral; it will probably be found in association with lukkulaisvaaraite and telargpalite or telluropalladinite, among other platinum-group minerals. The phasePd2+xAg2–x Te can be found in association with telargpalite. Mineral assemblages defined in this study can be expected in Cu-Ni-PGE mineral deposits, associated with mafic and ultramafic igneous rocks, particularly in mineralized zones with known silver-palladium tellurides.

Synthesis and crystal structure of (Ag,Pd)22Se6

2013 ◽  
Vol 28 (1) ◽  
pp. 13-17 ◽  
Author(s):  
F. Laufek ◽  
A. Vymazalová ◽  
D.A. Chareev ◽  
A.V. Kristavchuk ◽  
J. Drahokoupil ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Glass Tube ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Cell Parameters ◽  
Silica Glass Tube

The (Ag,Pd)22Se6 phase was synthesized from individual elements by silica glass tube technique and structurally characterized from powder X-ray diffraction data. The (Ag,Pd)22Se6 phase crystallizes in Fm$\overline3$m symmetry, unit-cell parameters: a = 12.3169(2) Å, V = 1862.55(5) Å3, Z = 4, and Dc = 10.01 g/cm3. The crystal structure of the (Ag,Pd)22Se6 phase represents a stuffed 3a.3a.3a superstructure of the Pd structure (fcc), where only 4 from 108 available octahedral holes are occupied. Its crystal structure is related to the Cr23C6 structure type.

The occurrence of gold in Voia deposit, South Apuseni Mountains, Romania

2021 ◽  
Author(s):  
Elena-Luisa Iatan
Keyword(s):  
Iron Oxides ◽  
Base Metal ◽  
Mineral Assemblage ◽  
Native Gold ◽  
Metal Sulfides ◽  
Volcanic Complex ◽  
Apuseni Mountains ◽  
Base Metal Sulfides ◽  
Mineral Assemblages ◽  
Phyllic Alteration

<p>Voia deposit belongs to the Săcărâmb-Cetraș-Cordurea Miocene volcano-tectonic alignment of the South Apuseni Mountains, Romania. This large volcanic complex represents a Sarmatian-Pannonian magmatic-hydrothemal mega-system of around 5 km<sup>2</sup> with an estimated 3–4 Ma time-space evolution, consisting of seven andesitic volcanic structures grouped in a circle, three subvolcanic andesite-quartz porphyry microdiorite and associated porphyry Cu-Au(Mo), pyrite Ca-Mg skarns and epithermal Au-Ag-Pb-Zn-Cu mineralizations.</p><p>The mineral assemblages of alteration and mineralization processes belong to several mineralized zones on a vertical scale, according to sampling evidence and laboratory studies. HS products are found in the upper part of the structure (300-500 m), with dominant advanced and intermediate argillic alterations and sulfide-sulfate gold-poor veins (pyrite, marcasite, base metal sulfides, Fe-Ti oxides, vuggy quartz, alunite, gypsum, anhydrite). Within the 500-1200 m depth, the HS mineral assemblages gradually decrease in favor of IS and LS products. It is characterized by the coexistence of gold-rich LS assemblage (native gold, base metal sulfide, adularia, sericite-illite, chlorite, carbonates ± anhydrite veins), with the IS assemblage (iron oxides, chalcopyrite, pyrite, quartz, anhydrite). These assemblages overprint the HS mineral associations, resulting in a transition zone characterized by gold - pyrite - chalcopyrite - iron oxides - quartz - anhydrite mineral assemblage characteristic for HS and native gold - pyrite - base metal sulfides - carbonates - quartz mineral assemblage corresponding to IS+LS type.</p><p>Gold is present in all of the identified mineralization forms: porphyry-epithermal Cu-Au, epi-mesothermal carbonate veins with gold - base metal sulfides, quartz veins with pyrite - chalcopyrite - magnetite ± hematite ± anhydrite, anhydrite veins with base metal sulfides and sulfosalts, anhydrite veins with pyrite - anhydrite ± quartz, vuggy quartz (silica residue) with gold-poor pyrite veins and impregnations in porphyry systems.</p><p>Drilling core samples revealed that in Voia deposit, gold is concentrated in chalcopyrite (drills no. 7, 19, 37) along with pyrite - magnetite - hematite - quartz assemblage from the late potassic stage. The major amount of gold associated with chalcopyrite tends to be mainly submicroscopic. Pyrite from anhydrite veins of the early potassic stage ± phyllic alteration is relatively poor in gold (drills no. 1-6, 8-14). However, the highest gold contents are present in pentagonal dodecahedron pyrites (drills no. 33, 38, 39) of pyrite-chalcopyrite-magnetite ± hematite-quartz assemblage from late potassic stage ± phyllic alteration. Pyrite associated with magnetite from anhydrite veins tends to be poor in gold (drills no. 8, 11, 15, 28, 29). A carbonate vein containing gold-bearing base metal sulfides that was intercepted at 960,00-960,30m depth by drill no. 17 is one of the richest in gold.</p><p>Native gold occurs as fine inclusions in ore minerals (5-20 μm). Large irregular grains of native gold (>50 μm) appear at mineral boundaries and along the fissures. The gold color is bright yellow and has a measured Au:Ag ratio of 5:1, suggesting that native gold has been formed at a relatively high temperature.</p><p>Acknowledgments: This work was supported by two Romanian Ministry of Research and Innovation grants: PN-III-P4-ID-PCCF-2016-4-0014 and PN-III-P1-1.2-PCCDI-2017-0346/29.</p>

Mineralization in the Bonser vein, Coniston, English Lake District: mineral assemblages, paragenesis, and formation conditions

1982 ◽  
Vol 46 (340) ◽  
pp. 343-350 ◽  
Author(s):  
C. J. Stanley ◽  
D. J. Vaughan
Keyword(s):  
Electron Microprobe ◽  
Mineral Assemblage ◽  
Oxygen Activity ◽  
British Isles ◽  
Lake District ◽  
Coexisting Phases ◽  
Mineral Assemblages ◽  
English Lake District ◽  
Formation Conditions ◽  
Native Bismuth

AbstractThe Bonser vein, one of the most productive sources of copper in the English Lake District, contains a mineral assemblage comprising quartz, chlorite, calcite, dolomite, stilpnomelane, magnetite, pyrrhotine, pyrite, marcasite, native bismuth, bismuthinite, laitakarite, joseite, arsenopyrite, chalcopyrite, sphalerite, galena, and cosalite. The phases pyrrhotine, sphalerite, arsenopyrite, laitakarite, joseite, and cosalite were analysed by electron microprobe. The occurrence of laitakarite is the first reported in the British Isles. Textures of the ore and gangue minerals show that the vein minerals were deposited successively in open voids. The sequence of deposition was of quartz forming throughout, early chlorite and stilpnomelane with some dolomite and calcite, magnetite as the earliest opaque phase, followed by arsenopyrite, pyrrhotine, sphalerite, chalcopyrite, pyrite, and marcasite; the bismuth- and lead-bearing minerals were the last to form.The data on the coexisting phases and their compositions have been used to estimate the temperatures of mineralization and the activities of sulphur and oxygen. Magnetite and arsenopyrite appear to have formed at 350–400% withaS2reaching 10−12to 10−14atm. andaO2around 10−24to 10−29atm. The assemblage of quartz, chlorite, stilpnomelane, calcite, dolomite, pyrrhoine, chalcopyrite, sphalerite, and (late) arsenopyrite was probably deposited at ∼ 240°C, withaS2decreasing to 10−15to 10−16atm andaO2to 10−38) to 10{su−44atm. The later minerals probably formed at temperatures as low as 200°C and under similar conditions of sulphur and oxygen activity.

Powder diffraction study of Pd2HgSe3

2017 ◽  
Vol 32 (4) ◽  
pp. 244-248 ◽  
Author(s):  
F. Laufek ◽  
A. Vymazalová ◽  
M. Drábek
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Silica Glass ◽  
Rietveld Method ◽  
Glass Tube ◽  
Layered Crystal ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Layered Crystal Structure ◽  
Silica Glass Tube

The Pd2HgSe3 phase was synthetized from individual elements by the silica glass tube technique and its crystal structure has been refined by the Rietveld method. The Pd2HgSe3 phase crystalizes in P$\bar 3$m1 space group with the unit-cell parameters a = 7.3096(2) Å, c = 5.2829(1) Å, V = 244.45(1) Å3, Dc = 8.84 g/cm3, and Z = 2. In its layered crystal structure, the [PdSe6] octahedra share opposing Se–Se edges with adjacent [PdSe4] squares forming layers parallel with the (001) plane. The layers show AA type stacking along the c-axis. Hg atoms occupy the anti-cubooctahedral voids between two consecutive layers. Pd2HgSe3 is isostructural with Pt2HgSe3 and Pt4Tl2X6 (X = S, Se, or Te) phases. The structure can be viewed as a 2a.2a.c superstructure of PtSe2.

Chapter 2 The Early Stages - Scourian and Inverian

2002 ◽  
Vol 26 (1) ◽  
pp. 11-20
Keyword(s):  
Mineral Assemblage ◽  
Dyke Swarm ◽  
Small Bodies ◽  
Mafic Mineral ◽  
Partial Recrystallization ◽  
Early Stages ◽  
Mineral Assemblages

Archaean gneisses occupy large areas on each side of the central NW-SE-trending belt formed by the outcrop of the Loch Maree Group (Fig. 2.1). They are cut by numerous amphibolite dykes of the 'Scourie dyke' swarm (see Chapter 3). The gneisses are predominantly granodioritic to tonalitic, quartzo-feldspathic biotite gneisses but large areas of more mafic hornblende gneiss occur in the NE, and small bodies of amphibolite are enclosed within the gneisses in all parts of the area.The gneisses have undergone a long and complex history, having experienced Scourian, Inverian, and Laxfordian thermotectonic events. Although Scourian structures have been preserved locally, little of the original Scourian mineral assemblage remains, and the mineral assemblages mainly reflect Inverian and Laxfordian recrystallizations (see Section 2.4).The quartzo-feldspathic biotite gneisses are pale grey to pinkish-weathering, banded or massive, granodioritic (or less commonly tonalitic) gneisses containing biotite as their main mafic mineral. The banded varieties show partial or complete segregation of micas into seperate layers or lenses (Fig. 2.2). Typical examoles contain oligoclase, quartz, microcline and a dark brown biotite, in varying proportions. Muscovite, chlorite or epidote may be present in addition, together with traces of opaque ore and apatite. The gneisses within several kilometres of the outcrop of the Loch Maree Group exhibit evidence of partial recrystallization from a coarsergrained assemblage, the larger feldspar grains being surrounded by granular aggregates of smaller grains feldspar and quartz. Chlorite and epidote are clearly replacive.Retrogressive recrystallization to an epidote-bearing assemblage is particularly marked on the SW

Platinum-group element mineralization in an As-rich magmatic sulphide system, Talnotry, southwest Scotland

2004 ◽  
Vol 68 (2) ◽  
pp. 395-411 ◽  
Author(s):  
M. R. Power ◽  
D. Pirrie ◽  
J. Jedwab ◽  
C. J. Stanley
Keyword(s):  
Solid Solution ◽  
Mineral Assemblage ◽  
Platinum Group Element ◽  
Group Element ◽  
Sulphide Mineralization ◽  
Group Mineral ◽  
Intermediate Solid Solution ◽  
Sulphide Liquid ◽  
Mineral Assemblages ◽  
Platinum Group

AbstractArsenic-rich magmatic sulphide mineralization is hosted by a diorite intrusion at Talnotry, southwest Scotland. A relatively abundant and diverse platinum-group mineral assemblage is present and is dominated by sperrylite, irarsite and electrum with subordinate merenskyite, michenerite and froodite. Early euhedral gersdorffite is enriched with respect to Rh, Ir and Pt and in some cases contains exsolved blebs of irarsite or euhedral grains of sperrylite. Sperrylite is also enclosed within silicates and sulphides indicating that it crystallized directly from an As-rich sulphide liquid. Pyrrhotite-chalcopyrite mineral assemblages are consistent with the fractional crystallization of monosulphide solid solution and are overlain by PGE-, Ni- and As-rich mineral assemblages indicative of crystallization from a NiAs liquid. Late-stage, cross-cutting, electrum-bearing chalcopyrite veins are consistent with the crystallization of Cu- and Au-rich intermediate solid solution. The chemistry, mineralogy and lithological relationships of the diorite suggest that it may be an appinite and as such is potentially analogous to the Au-rich lamprophyre dykes present within southwest Scotland.

Metamorphism of the Thompson nickel belt gneisses: Paint Lake, Manitoba

1981 ◽  
Vol 18 (2) ◽  
pp. 191-209 ◽  
Author(s):  
J. K. Russell
Keyword(s):  
Mineral Assemblage ◽  
Total Pressure ◽  
Controlling Factor ◽  
Amphibolite Facies ◽  
Metamorphic Event ◽  
Mineral Phase ◽  
Mineral Assemblages ◽  
Temperature And Pressure ◽  
Granulite Terrain ◽  
Detailed Work

Gneisses mapped in the Thompson nickel belt are the product of a Hudsonian metamorphic (M3) overprinting of an Archean granulite terrain. Pikwitonei region granulites may be partially preserved in amphibolite facies migmatite gneisses of the Thompson nickel belt. Temperatures attending the earlier Archean (M2) metamorphic event have been estimated to be 910 ± 70 °C. More detailed work on the younger overprinting suggests that the metamorphic conditions were relatively constant during the M3 metamorphism. Estimated temperature and pressure during the Hudsonian metamorphism are 650 ± 50 °C and 4–5 kbar (4–5 × 105 kPa), respectively.Although total pressure may have been constant, calculated values for [Formula: see text] during the retrograde overprinting indicate a variability due to lithologic control. This variability in [Formula: see text] is shown to be a controlling factor in the development of hydrous retrograde mineral assemblages. Metapelitic gneisses are characterized by [Formula: see text] values of 0.05Ptotal, which may explain the absence of muscovite as a stable M3 mineral phase. Enderbitic gneisses exhibit higher values of [Formula: see text] (0.25Ptotal) due to the emplacement of syn-M3 pegmatite dykes producing a more hydrous stable M3 mineral assemblage.

Silver-palladium alloy particle production by spray pyrolysis

1995 ◽  
Vol 10 (7) ◽  
pp. 1661-1673 ◽  
Author(s):  
Tammy C. Pluym ◽  
Toivo T. Kodas ◽  
Lu-Min Wang ◽  
Howard D. Glicksman
Keyword(s):  
Spray Pyrolysis ◽  
Reaction Temperature ◽  
Particle Production ◽  
Precursor Solution ◽  
Metal Nitrate ◽  
Particle Phase ◽  
Alloy Particles ◽  
Nitrate Precursor ◽  
Pd Alloy ◽  
Silver Palladium

Spray pyrolysis was used to produce submicron Ag-Pd metal alloy particles for applications in electronic component fabrication. The particles were prepared in nitrogen carrier gas from metal nitrate precursor solutions with various compositions. The Ag-Pd alloy was the predominant phase for reactor temperatures of 700 °C and above for all compositions. The 70-30 Ag-Pd partcles were fully dense at 700 °C, but an increased reaction temperature was necessary to produce dense particles at higher Pd to Ag ratios. The extent of palladium oxidation was suppressed with increased amounts of Ag. Single-crystal particles could be produced at sufficiently high temperatures. These results show that particle phase composition, size, oxidation behavior, and morphology can be controlled by the Ag-Pd ratio in the precursor solution and by the reaction temperature.

A re-examination of herzenbergite–teallite solid solution at temperatures between 300 and 700°C

2001 ◽  
Vol 65 (5) ◽  
pp. 645-651 ◽  
Author(s):  
K. Hayashi ◽  
A. Kitakaze ◽  
A. Sugaki
Keyword(s):  
Solid Solution ◽  
Linear Relationship ◽  
Silica Glass ◽  
Glass Tube ◽  
Solid Solution Series ◽  
Solution Series ◽  
Cell Dimensions ◽  
Silica Glass Tube

AbstractIn order to investigate the range of the solid solution series in herzenbergite-teallite minerals, samples of different composition were synthesized. Herzenbergite-teallite minerals were synthesized by an evacuated silica glass tube method at 700°C. A linear relationship between cell dimensions, a, b and c and composition is established. Extension of solid solution to the Pb-rich portion of the system PbS-SnS is limited; the solid solution area is between Pb1.060Sn0.940S2 and SnS at 700°C. Teallite coexisting with galena was also synthesized by hydrothermal recrystallization at 300, 400 and 450°C. The compositions of teallite are Pb1.140Sn0.860S2 at 300°C, Pb1.114Sn0.886S2 at 400°C, and Pb1.124Sn0.876S2 at 450°C, respectively. Their compositions shift towards the PbS end-member from stoichiometric teallite. The cell dimensions of teallite, which was synthesized hydrothermally, follow the linear relationship between cell dimensions and composition established at 700°C.

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