Mineral Deposit Research: Meeting the Global Challenge, 2005
The igneous rocks, some geological specifics, and also the very melt inclusions in Late Cenozoic ... more The igneous rocks, some geological specifics, and also the very melt inclusions in Late Cenozoic rhyolites were studied in the long-lived Miocene (N1, ca. 20 Ma)-Late Quaternary (Q3?) Bazman volcano, eastern Iran. Unusual low temperature (ca. 690o C) silicate melt inclusions in quartz (Qtz) with a High/very High water content (from average 6.9 to 8.2 (up to 9.0 as a limit) wt% H2O) in the acid rocks were defined by independent methods for the first time. Whole-rock chemistry of the melts studied is similar to ones in subduction-related acid melts from different regions. Rhyolites studied sometimes have higher concentration of ore elements, similar to ones in even basites. Ore inheritance from economic porphyry-PCD (Cu-Au +-Mo) Paleogene (mainly Eocene-Pg2) mineralization and deposits in the region is proposed. Geological anomaly of the whole region is proposed by a complex analysis. This anomaly is maybe responsible for anomalous magmatism due to a known tomography data (since Paleocene (Pg1), as minimum), tectonics, metallogeny (including economic one), and maybe-hydrocarbons (HC, oil-gas) activity.
Synthetic nagyagite was grown from a melt as part of a search for materials with high-temperature... more Synthetic nagyagite was grown from a melt as part of a search for materials with high-temperature superconductivity. Electron microprobe analyses of synthetic nagyagite and of nagyagite from the type locality Nagyág, Transylvania (now Sȃcȃrîmb, Romania) agree with data from literature. The crystal chemical formula [Pb(Pb,Sb)S 2 ][(Au,Te)] was derived from crystal structure investigations. Nagyagite is monoclinic pseudotetragonal. The average crystal structure was determined from both synthetic and natural samples and was refined from the synthetic material to R = 0.045 for 657 single-crystal X-ray data: space group P2 1 /m, a = 4.220(1) Å, b = 4.176(1) Å, c = 15.119(3) Å, β = 95.42(3)°, and Z = 2. Nagyagite features a pronounced layer structure: slices of a two slabs thick SnS-archetype with formula Pb(Pb,Sb)S 2 parallel to (001) have a thickness of 9.15 Å. Te and Au form a planar pseudo-square net that is sandwiched between the SnS-archetype layers; it is assumed that planar Au [4Te] Te 4 configurations are edge connected to chains and that Te atoms are in a zigzag arrangement. Ordering within the SnS-archetype and gold-tellurium layers, intense twinning and/or stacking variants are responsible for the often observed superstructure reflections. For buckhornite, [(Pb 2 Bi) ∑3 S 3 ][(AuTe 2 ) ∑3 ], a structure model is proposed considering a homologous series with nagyagite, [(Pb 3 (Pb,Sb) 3 ) ∑6 S 6 ][(Au,Te) 3 ].
ABSIRACT .Donharrisite, idealy NisHg3S9, is a new mineral species found on a museum specimen from... more ABSIRACT .Donharrisite, idealy NisHg3S9, is a new mineral species found on a museum specimen from the former Erasmus miue, Schwardsp mining district, Leogang, Salzburg Province, Austria. The specimen is probably taken from a stratabound carbonate-hosted Pb-Ag-He ore. The new minoal species occurs as browuish metallic, mica-like flakes up to I mm2 by 0.1 mm thick, associated witl cinnabar, native mocury, galena and trace amounts of spbalerite, tetrnantite, chalcopyrite, polydpdte and pyrite, on slickensided dolostone. It is brittle, opaque, with a brownish grey streak, a perfect cleavage parallel {001} and a pronounced conchoidal fracture. VHNs = 4? (av. of 7), Dcab = 5.18 g/cm3 for tle ideal foimula, and 5.17 g/cmr for.tle empirical formula with Z = 2,In reflected ligbt, I e mineral is creamy white witl a yellowish tint in air, and creamy white in oil. Anisotropism, in greyish colors, is distinct in both air and oil. Reflectance spectra and color values for two grains aro tabulated. Electron-microprobe analyses show very little variation in chenical composition; the mean values for 7 analyses are: Ni 35.2, Hg 43,3, S 20.6, total 99. 1 wt. 9o . The empirical formda (on the basis of 20 atoms) is Nfu.2Hg2.e6ft32. Dgnharrisite is monoclinic, a 11.66{3), , 6.91(1), c lO.92Q) A, P 97,43(20), space grovp C2/m, C2 or C4. The strongest six X-ray powderdiffraction lines ld in A g)@kl)l are:_ 5.75(70)(200), J.ogfoxllr), 3.7 l (50X202), 3.33(60)(3 l l), 2.683(60)(4O2,2.22) and 2.547(lW)(nD. The oame honors Dr. Donald C. Harris for his major contributions to the mineralogy.of ores.
Suredaite, ideally PbSnS 3 , is a new mineral species from the Pirquitas Ag-Sn deposit (Province ... more Suredaite, ideally PbSnS 3 , is a new mineral species from the Pirquitas Ag-Sn deposit (Province Jujuy, NW-Argentina). It was observed in symmetrically banded veins in the Oploca district, and is associated with sphalerite, arsenopyrite, pyrite-marcasite, cassiterite, cylindrite, franckeite, hocartite, rhodostannite, and various Ag-Sb and Ag-Bi sulfosalts in minor amounts. Suredaite occurs in layers up to 1 cm in thickness as aggregates of radially arranged tabular-prismatic (single) crystals, has a metallic lustre, and a dark grey streak. VHN 50 ranges between 18.2 and 20.6 (mean 19.6) GPa, the Mohs hardness is 2.5-3. It has perfect cleavages parallel to {001}, {101}, and {100}. The measured density varies between 5.54 and 5.88 g/cm 3 , D x was determined to be 5.615 g/cm 3 . In reflected plane-polarised light, it is white and is not perceptibly bireflectant or pleochroic. It lacks internal reflections and is weakly anisotropic with metallic blue, mauve to brown rotation tints. Specular reflectance percentages in air and in oil are tabulated from 400 to 700 nm and compared graphically with those for the type specimen of teallite, PbSnS 2 . Electron microprobe analyses showed suredaite to be chemically inhomogeneous with respect to the compositional variations (in wt%): Pb 42.3-48.5, Ag 0.3-1.1, Fe 0.3-1.0, As 0.2-2.1, Sn 27.7-30.2, S 23.1-24.7. The crystal structure determined from single-crystal X-ray diffraction data revealed orthorhombic symmetry [space group Pnma, Z = 4, a = 8.8221(3), b = 3.7728(3), c = 14.0076(3) Å; V = 466.23(4) Å 3 ]. The atomic arrangement is isostructural to the NH 4 CdCl 3 structure type which exists in a series of isotypic sulfides and selenide compounds. The suredaite structure, which is the natural analogue of synthetic PbSnS 3 , consists of columns of double-edge sharing octahedra running parallel to the b axis, which house the Sn atoms. These columns are linked by rods of eightfold-coordinated Pb atoms. On the basis of the structure determination, the empirically determined idealized formula follows a [8] (Pb, As,Ag, Sn) [6] (Sn,Fe)S 3 stoichiometry. Crystalchemical arguments suggest Ag possibly to occupy interstitial sites according to the alternative formula [4] (s,Ag) [8] (Pb, As, Sn) [6] (Sn,Fe) S 3 . The name of this new mineral species is in honor of R.J. Sureda Leston, head of the
Synthetic nagyagite was grown from a melt as part of a search for materials with high-temperature... more Synthetic nagyagite was grown from a melt as part of a search for materials with high-temperature superconductivity. Electron microprobe analyses of synthetic nagyagite and of nagyagite from the type locality Nagyág, Transylvania (now Sȃcȃrîmb, Romania) agree with data from literature. The crystal chemical formula [Pb(Pb,Sb)S 2 ][(Au,Te)] was derived from crystal structure investigations. Nagyagite is monoclinic pseudotetragonal. The average crystal structure was determined from both synthetic and natural samples and was refined from the synthetic material to R = 0.045 for 657 single-crystal X-ray data: space group P2 1 /m, a = 4.220(1) Å, b = 4.176(1) Å, c = 15.119(3) Å, β = 95.42(3)°, and Z = 2. Nagyagite features a pronounced layer structure: slices of a two slabs thick SnS-archetype with formula Pb(Pb,Sb)S 2 parallel to (001) have a thickness of 9.15 Å. Te and Au form a planar pseudo-square net that is sandwiched between the SnS-archetype layers; it is assumed that planar Au [4Te] Te 4 configurations are edge connected to chains and that Te atoms are in a zigzag arrangement. Ordering within the SnS-archetype and gold-tellurium layers, intense twinning and/or stacking variants are responsible for the often observed superstructure reflections. For buckhornite, [(Pb 2 Bi) ∑3 S 3 ][(AuTe 2 ) ∑3 ], a structure model is proposed considering a homologous series with nagyagite, [(Pb 3 (Pb,Sb) 3 ) ∑6 S 6 ][(Au,Te) 3 ].
Mineral Deposit Research: Meeting the Global Challenge, 2005
The occurrence ofTe-bearing species in different deposit types of Argentina is reviewed. Tellurid... more The occurrence ofTe-bearing species in different deposit types of Argentina is reviewed. Tellurides with Au and/or Ag are especially abundant in epithermal environments of the high-and low-sulphidation states whereas those with Ag and Sn may prevail in Ag-5n deposits.In very few cases (La Mejicana, Famatina; Farallön Negro) Auand/or Ag-bearing tellurides contribute to the grade of these elements in the ore and thus are of economic imoortance. A great part of the deposits which contain tellurides is structurally controlled and genetically related with the Miocene to Pliocene volcanism.
Qualitative optical properties are described, and reflec- tance spectra provided, for cotype mont... more Qualitative optical properties are described, and reflec- tance spectra provided, for cotype montbrayite, from the Robb Montbray mine, Quebec, together with the results of electron-microprobe analyses. The optical data are com- pared with data for all of the known gold telluride minglal5; microscope-spectrophotometry is found to be a useful tech- nique to distinguish the different minerals. Attention is drawn to
Revista De La Asociacion Geologica Argentina, Jun 1, 2009
... In contrary, Pb-Zn-rich intermediate-sulfi-dation ore is usually poor in Ag as galena does no... more ... In contrary, Pb-Zn-rich intermediate-sulfi-dation ore is usually poor in Ag as galena does not contain any silver. Within the Ag-rich ore shoots of the La Argentina vein, the silver carriers are native silver, acanthite, proustite, pearceite and argyro-dite (Putz 2005; Figs. ...
Revista De La Asociacion Geologica Argentina, Jun 1, 2009
The Capillitas deposit is part of the Farallón Negro Volcanic Complex, Catamarca Province, northw... more The Capillitas deposit is part of the Farallón Negro Volcanic Complex, Catamarca Province, northwestern Argentina. The epithermal mineralization is related to the Capillitas diatreme, a volcanic pipe composed of intrusive and volcanoclastic rocks of rhyolitic to dacitic composition of Miocene age which is located in the granitic basement block of the Sierra de Capillitas. The deposit consists of numerous mineralized veins which crosscut the diatreme volcanics and the adjacent Capillitas granite. The different geological environments, the alteration features and the ore mineralogy enable to distinguish between highand intermediate-sulfidation environments, which are overprinted by supergene processes. The first group is accompanied by advanced argillic alteration and silicification and in the second rhodochrosite and quartz are the predominant gangue minerals. The polymetallic character of the Capillitas epithermal deposit is clearly emphasized by its complex Cu-Pb-Zn-Fe-Mn-As-Sb paragenesis, with minor W, Bi, Sn, Te, Ag and Au and traces of Ge, Cd, In, V, Ni and Tl, present in more than 150 different minerals. Additionally, Capillitas represents the type locality for the two new mineral species putzite and catamarcaite. The hydrothermal vein system at Capillitas was formed under strongly changing p-T-X conditions. Cu, As, Te, Sn, Bi and Au represent the key metals of the high-sulfidation stage whereas the metal association Zn-Pb-Ag is typical for the intermediate-sulfidation stage. Based on fluid inclusion studies, the Capillitas deposit can be characterized by temperatures of ore formation mostly below 300 °C and low salinities (< 6 wt. % NaCl equivalent).
Baumstarkite is a new mineral found coating miargyrite from the San Genaro mine, Huancavelica Dep... more Baumstarkite is a new mineral found coating miargyrite from the San Genaro mine, Huancavelica Department, Peru. It is triclinic and the third naturally occurring modification of AgSbS 2 besides monoclinic miargyrite and cubic cuboargyrite. The composition is usually close to the ideal formula. However, some grains of baumstarkite show zoned lamellae with As contents up to 11.5 wt% and accords to Ag 3 (Sb,As) 2 SbS 6 . Baumstarkite is isotypic with aramayoite [end-member composition Ag 3 Sb 2 BiS 6 ; solid solutions require the extended formula Ag 3 Sb 2 (Bi,Sb)S 6 ]. Single-crystal Xray structure investigations were performed for baumstarkite [type locality, a = 7.766 , b = 8.322(2), c = 8.814(2) Å, a = 100.62(2), b = 104.03(2), g = 90.22(2)∞, Z = 2{Ag 3 Sb 3 S 6 }, space group P1 -, R1(F) = 0.057, wR 2 (F 2 ) = 0.128], aramayoite [Armonia mine, El Quevar, Argentinia: a = 7.813(2), b = 8.268(2), c = 8.880(2) Å, a = 100.32(2), b = 104.07(2), g = 90.18(2)∞, Z = 2{Ag 3 Sb 2 S 6 }, space group P1 -, R1(F) = 0.034, wR2(F 2 ) = 0.084], and miargyrite associated with baumstarkite type material [a = 12.862(3), b = 4.409(1), c = 13.218(3) Å, b = 98.48(2)∞, Z = 8{AgSbS 2 }, space group C2/c, R1(F) = 0.031, wR2(F 2 ) = 0.082].
Qualitative optical properties are described, and reflectance spectra provided, for cotype montbr... more Qualitative optical properties are described, and reflectance spectra provided, for cotype montbrayite, from the Robb Montbray mine, Quebec, together with the results of electron-microprobe analyses. The optical data are compared with data for all of the known gold telluride minglal5; microscope-spectrophotometry is found to be a useful technique to distinguish the different minerals. Attention is drawn to discrepancies between reflectance spectra measured with singleand double-beam microscopespectrophotometers.
Suredaite, ideally PbSnS 3 , is a new mineral species from the Pirquitas Ag-Sn deposit (Province ... more Suredaite, ideally PbSnS 3 , is a new mineral species from the Pirquitas Ag-Sn deposit (Province Jujuy, NW-Argentina). It was observed in symmetrically banded veins in the Oploca district, and is associated with sphalerite, arsenopyrite, pyrite-marcasite, cassiterite, cylindrite, franckeite, hocartite, rhodostannite, and various Ag-Sb and Ag-Bi sulfosalts in minor amounts. Suredaite occurs in layers up to 1 cm in thickness as aggregates of radially arranged tabular-prismatic (single) crystals, has a metallic lustre, and a dark grey streak. VHN 50 ranges between 18.2 and 20.6 (mean 19.6) GPa, the Mohs hardness is 2.5-3. It has perfect cleavages parallel to {001}, {101}, and {100}. The measured density varies between 5.54 and 5.88 g/cm 3 , D x was determined to be 5.615 g/cm 3 . In reflected plane-polarised light, it is white and is not perceptibly bireflectant or pleochroic. It lacks internal reflections and is weakly anisotropic with metallic blue, mauve to brown rotation tints. Specular reflectance percentages in air and in oil are tabulated from 400 to 700 nm and compared graphically with those for the type specimen of teallite, PbSnS 2 . Electron microprobe analyses showed suredaite to be chemically inhomogeneous with respect to the compositional variations (in wt%): Pb 42.3-48.5, Ag 0.3-1.1, Fe 0.3-1.0, As 0.2-2.1, Sn 27.7-30.2, S 23.1-24.7. The crystal structure determined from single-crystal X-ray diffraction data revealed orthorhombic symmetry [space group Pnma, Z = 4, a = 8.8221(3), b = 3.7728(3), c = 14.0076(3) Å; V = 466.23(4) Å 3 ]. The atomic arrangement is isostructural to the NH 4 CdCl 3 structure type which exists in a series of isotypic sulfides and selenide compounds. The suredaite structure, which is the natural analogue of synthetic PbSnS 3 , consists of columns of double-edge sharing octahedra running parallel to the b axis, which house the Sn atoms. These columns are linked by rods of eightfold-coordinated Pb atoms. On the basis of the structure determination, the empirically determined idealized formula follows a [8] (Pb, As,Ag, Sn) [6] (Sn,Fe)S 3 stoichiometry. Crystalchemical arguments suggest Ag possibly to occupy interstitial sites according to the alternative formula [4] (s,Ag) [8] (Pb, As, Sn) [6] (Sn,Fe) S 3 . The name of this new mineral species is in honor of R.J. Sureda Leston, head of the
Baumstarkite is a new mineral found coating miargyrite from the San Genaro mine, Huancavelica Dep... more Baumstarkite is a new mineral found coating miargyrite from the San Genaro mine, Huancavelica Department, Peru. It is triclinic and the third naturally occurring modification of AgSbS 2 besides monoclinic miargyrite and cubic cuboargyrite. The composition is usually close to the ideal formula. However, some grains of baumstarkite show zoned lamellae with As contents up to 11.5 wt% and accords to Ag 3 (Sb,As) 2 SbS 6 . Baumstarkite is isotypic with aramayoite [end-member composition Ag 3 Sb 2 BiS 6 ; solid solutions require the extended formula Ag 3 Sb 2 (Bi,Sb)S 6 ]. Single-crystal Xray structure investigations were performed for baumstarkite [type locality, a = 7.766 , b = 8.322(2), c = 8.814(2) Å, a = 100.62(2), b = 104.03(2), g = 90.22(2)∞, Z = 2{Ag 3 Sb 3 S 6 }, space group P1 -, R1(F) = 0.057, wR 2 (F 2 ) = 0.128], aramayoite [Armonia mine, El Quevar, Argentinia: a = 7.813(2), b = 8.268(2), c = 8.880(2) Å, a = 100.32(2), b = 104.07(2), g = 90.18(2)∞, Z = 2{Ag 3 Sb 2 S 6 }, space group P1 -, R1(F) = 0.034, wR2(F 2 ) = 0.084], and miargyrite associated with baumstarkite type material [a = 12.862(3), b = 4.409(1), c = 13.218(3) Å, b = 98.48(2)∞, Z = 8{AgSbS 2 }, space group C2/c, R1(F) = 0.031, wR2(F 2 ) = 0.082].
Germanium is enriched in several epithermal deposits of Bolivia and Argentina. Pb-Zn-Ag deposits ... more Germanium is enriched in several epithermal deposits of Bolivia and Argentina. Pb-Zn-Ag deposits of the Bolivian silver-tin belt may contain high-grade Ge mineralization. Ge is present as the mineral argyrodite, AgsGeS6, which is usually associated with a bonanza-grade silver mineralization composed of Ag-sulfosalts (pyrargyrite, stephanite, polybasite, diaphorite), native silver and acanthite. A significant anomaly of Ge was detected in Ag-enriched ore shoots of the Porco deposit. Ge also occurs in polymetallic and precious metal-bearing ore at Capillitas, Argentina. Ge is either bound to the mineral argyrodite, thus similar to the deposits in Bolivia, or present in supergene enriched copper ore of the La Rosario vein. The latter paragenesis is characterized by distinct Ge minerals such as putzite, catamarcaite, " Ge-stannoidite " (all of them represent new mineral species) and briartite which are associated with high-grade chalcocite-bornite ore. The Ge mineralization of Bolivia and Argentina was generated in an epithermal environment of either low-sulphidation (Ag-Zn-Pb) or high-sulphidation (Cu-As-Au-W) type.
Mineral Deposit Research: Meeting the Global Challenge, 2005
The igneous rocks, some geological specifics, and also the very melt inclusions in Late Cenozoic ... more The igneous rocks, some geological specifics, and also the very melt inclusions in Late Cenozoic rhyolites were studied in the long-lived Miocene (N1, ca. 20 Ma)-Late Quaternary (Q3?) Bazman volcano, eastern Iran. Unusual low temperature (ca. 690o C) silicate melt inclusions in quartz (Qtz) with a High/very High water content (from average 6.9 to 8.2 (up to 9.0 as a limit) wt% H2O) in the acid rocks were defined by independent methods for the first time. Whole-rock chemistry of the melts studied is similar to ones in subduction-related acid melts from different regions. Rhyolites studied sometimes have higher concentration of ore elements, similar to ones in even basites. Ore inheritance from economic porphyry-PCD (Cu-Au +-Mo) Paleogene (mainly Eocene-Pg2) mineralization and deposits in the region is proposed. Geological anomaly of the whole region is proposed by a complex analysis. This anomaly is maybe responsible for anomalous magmatism due to a known tomography data (since Paleocene (Pg1), as minimum), tectonics, metallogeny (including economic one), and maybe-hydrocarbons (HC, oil-gas) activity.
Synthetic nagyagite was grown from a melt as part of a search for materials with high-temperature... more Synthetic nagyagite was grown from a melt as part of a search for materials with high-temperature superconductivity. Electron microprobe analyses of synthetic nagyagite and of nagyagite from the type locality Nagyág, Transylvania (now Sȃcȃrîmb, Romania) agree with data from literature. The crystal chemical formula [Pb(Pb,Sb)S 2 ][(Au,Te)] was derived from crystal structure investigations. Nagyagite is monoclinic pseudotetragonal. The average crystal structure was determined from both synthetic and natural samples and was refined from the synthetic material to R = 0.045 for 657 single-crystal X-ray data: space group P2 1 /m, a = 4.220(1) Å, b = 4.176(1) Å, c = 15.119(3) Å, β = 95.42(3)°, and Z = 2. Nagyagite features a pronounced layer structure: slices of a two slabs thick SnS-archetype with formula Pb(Pb,Sb)S 2 parallel to (001) have a thickness of 9.15 Å. Te and Au form a planar pseudo-square net that is sandwiched between the SnS-archetype layers; it is assumed that planar Au [4Te] Te 4 configurations are edge connected to chains and that Te atoms are in a zigzag arrangement. Ordering within the SnS-archetype and gold-tellurium layers, intense twinning and/or stacking variants are responsible for the often observed superstructure reflections. For buckhornite, [(Pb 2 Bi) ∑3 S 3 ][(AuTe 2 ) ∑3 ], a structure model is proposed considering a homologous series with nagyagite, [(Pb 3 (Pb,Sb) 3 ) ∑6 S 6 ][(Au,Te) 3 ].
ABSIRACT .Donharrisite, idealy NisHg3S9, is a new mineral species found on a museum specimen from... more ABSIRACT .Donharrisite, idealy NisHg3S9, is a new mineral species found on a museum specimen from the former Erasmus miue, Schwardsp mining district, Leogang, Salzburg Province, Austria. The specimen is probably taken from a stratabound carbonate-hosted Pb-Ag-He ore. The new minoal species occurs as browuish metallic, mica-like flakes up to I mm2 by 0.1 mm thick, associated witl cinnabar, native mocury, galena and trace amounts of spbalerite, tetrnantite, chalcopyrite, polydpdte and pyrite, on slickensided dolostone. It is brittle, opaque, with a brownish grey streak, a perfect cleavage parallel {001} and a pronounced conchoidal fracture. VHNs = 4? (av. of 7), Dcab = 5.18 g/cm3 for tle ideal foimula, and 5.17 g/cmr for.tle empirical formula with Z = 2,In reflected ligbt, I e mineral is creamy white witl a yellowish tint in air, and creamy white in oil. Anisotropism, in greyish colors, is distinct in both air and oil. Reflectance spectra and color values for two grains aro tabulated. Electron-microprobe analyses show very little variation in chenical composition; the mean values for 7 analyses are: Ni 35.2, Hg 43,3, S 20.6, total 99. 1 wt. 9o . The empirical formda (on the basis of 20 atoms) is Nfu.2Hg2.e6ft32. Dgnharrisite is monoclinic, a 11.66{3), , 6.91(1), c lO.92Q) A, P 97,43(20), space grovp C2/m, C2 or C4. The strongest six X-ray powderdiffraction lines ld in A g)@kl)l are:_ 5.75(70)(200), J.ogfoxllr), 3.7 l (50X202), 3.33(60)(3 l l), 2.683(60)(4O2,2.22) and 2.547(lW)(nD. The oame honors Dr. Donald C. Harris for his major contributions to the mineralogy.of ores.
Suredaite, ideally PbSnS 3 , is a new mineral species from the Pirquitas Ag-Sn deposit (Province ... more Suredaite, ideally PbSnS 3 , is a new mineral species from the Pirquitas Ag-Sn deposit (Province Jujuy, NW-Argentina). It was observed in symmetrically banded veins in the Oploca district, and is associated with sphalerite, arsenopyrite, pyrite-marcasite, cassiterite, cylindrite, franckeite, hocartite, rhodostannite, and various Ag-Sb and Ag-Bi sulfosalts in minor amounts. Suredaite occurs in layers up to 1 cm in thickness as aggregates of radially arranged tabular-prismatic (single) crystals, has a metallic lustre, and a dark grey streak. VHN 50 ranges between 18.2 and 20.6 (mean 19.6) GPa, the Mohs hardness is 2.5-3. It has perfect cleavages parallel to {001}, {101}, and {100}. The measured density varies between 5.54 and 5.88 g/cm 3 , D x was determined to be 5.615 g/cm 3 . In reflected plane-polarised light, it is white and is not perceptibly bireflectant or pleochroic. It lacks internal reflections and is weakly anisotropic with metallic blue, mauve to brown rotation tints. Specular reflectance percentages in air and in oil are tabulated from 400 to 700 nm and compared graphically with those for the type specimen of teallite, PbSnS 2 . Electron microprobe analyses showed suredaite to be chemically inhomogeneous with respect to the compositional variations (in wt%): Pb 42.3-48.5, Ag 0.3-1.1, Fe 0.3-1.0, As 0.2-2.1, Sn 27.7-30.2, S 23.1-24.7. The crystal structure determined from single-crystal X-ray diffraction data revealed orthorhombic symmetry [space group Pnma, Z = 4, a = 8.8221(3), b = 3.7728(3), c = 14.0076(3) Å; V = 466.23(4) Å 3 ]. The atomic arrangement is isostructural to the NH 4 CdCl 3 structure type which exists in a series of isotypic sulfides and selenide compounds. The suredaite structure, which is the natural analogue of synthetic PbSnS 3 , consists of columns of double-edge sharing octahedra running parallel to the b axis, which house the Sn atoms. These columns are linked by rods of eightfold-coordinated Pb atoms. On the basis of the structure determination, the empirically determined idealized formula follows a [8] (Pb, As,Ag, Sn) [6] (Sn,Fe)S 3 stoichiometry. Crystalchemical arguments suggest Ag possibly to occupy interstitial sites according to the alternative formula [4] (s,Ag) [8] (Pb, As, Sn) [6] (Sn,Fe) S 3 . The name of this new mineral species is in honor of R.J. Sureda Leston, head of the
Synthetic nagyagite was grown from a melt as part of a search for materials with high-temperature... more Synthetic nagyagite was grown from a melt as part of a search for materials with high-temperature superconductivity. Electron microprobe analyses of synthetic nagyagite and of nagyagite from the type locality Nagyág, Transylvania (now Sȃcȃrîmb, Romania) agree with data from literature. The crystal chemical formula [Pb(Pb,Sb)S 2 ][(Au,Te)] was derived from crystal structure investigations. Nagyagite is monoclinic pseudotetragonal. The average crystal structure was determined from both synthetic and natural samples and was refined from the synthetic material to R = 0.045 for 657 single-crystal X-ray data: space group P2 1 /m, a = 4.220(1) Å, b = 4.176(1) Å, c = 15.119(3) Å, β = 95.42(3)°, and Z = 2. Nagyagite features a pronounced layer structure: slices of a two slabs thick SnS-archetype with formula Pb(Pb,Sb)S 2 parallel to (001) have a thickness of 9.15 Å. Te and Au form a planar pseudo-square net that is sandwiched between the SnS-archetype layers; it is assumed that planar Au [4Te] Te 4 configurations are edge connected to chains and that Te atoms are in a zigzag arrangement. Ordering within the SnS-archetype and gold-tellurium layers, intense twinning and/or stacking variants are responsible for the often observed superstructure reflections. For buckhornite, [(Pb 2 Bi) ∑3 S 3 ][(AuTe 2 ) ∑3 ], a structure model is proposed considering a homologous series with nagyagite, [(Pb 3 (Pb,Sb) 3 ) ∑6 S 6 ][(Au,Te) 3 ].
Mineral Deposit Research: Meeting the Global Challenge, 2005
The occurrence ofTe-bearing species in different deposit types of Argentina is reviewed. Tellurid... more The occurrence ofTe-bearing species in different deposit types of Argentina is reviewed. Tellurides with Au and/or Ag are especially abundant in epithermal environments of the high-and low-sulphidation states whereas those with Ag and Sn may prevail in Ag-5n deposits.In very few cases (La Mejicana, Famatina; Farallön Negro) Auand/or Ag-bearing tellurides contribute to the grade of these elements in the ore and thus are of economic imoortance. A great part of the deposits which contain tellurides is structurally controlled and genetically related with the Miocene to Pliocene volcanism.
Qualitative optical properties are described, and reflec- tance spectra provided, for cotype mont... more Qualitative optical properties are described, and reflec- tance spectra provided, for cotype montbrayite, from the Robb Montbray mine, Quebec, together with the results of electron-microprobe analyses. The optical data are com- pared with data for all of the known gold telluride minglal5; microscope-spectrophotometry is found to be a useful tech- nique to distinguish the different minerals. Attention is drawn to
Revista De La Asociacion Geologica Argentina, Jun 1, 2009
... In contrary, Pb-Zn-rich intermediate-sulfi-dation ore is usually poor in Ag as galena does no... more ... In contrary, Pb-Zn-rich intermediate-sulfi-dation ore is usually poor in Ag as galena does not contain any silver. Within the Ag-rich ore shoots of the La Argentina vein, the silver carriers are native silver, acanthite, proustite, pearceite and argyro-dite (Putz 2005; Figs. ...
Revista De La Asociacion Geologica Argentina, Jun 1, 2009
The Capillitas deposit is part of the Farallón Negro Volcanic Complex, Catamarca Province, northw... more The Capillitas deposit is part of the Farallón Negro Volcanic Complex, Catamarca Province, northwestern Argentina. The epithermal mineralization is related to the Capillitas diatreme, a volcanic pipe composed of intrusive and volcanoclastic rocks of rhyolitic to dacitic composition of Miocene age which is located in the granitic basement block of the Sierra de Capillitas. The deposit consists of numerous mineralized veins which crosscut the diatreme volcanics and the adjacent Capillitas granite. The different geological environments, the alteration features and the ore mineralogy enable to distinguish between highand intermediate-sulfidation environments, which are overprinted by supergene processes. The first group is accompanied by advanced argillic alteration and silicification and in the second rhodochrosite and quartz are the predominant gangue minerals. The polymetallic character of the Capillitas epithermal deposit is clearly emphasized by its complex Cu-Pb-Zn-Fe-Mn-As-Sb paragenesis, with minor W, Bi, Sn, Te, Ag and Au and traces of Ge, Cd, In, V, Ni and Tl, present in more than 150 different minerals. Additionally, Capillitas represents the type locality for the two new mineral species putzite and catamarcaite. The hydrothermal vein system at Capillitas was formed under strongly changing p-T-X conditions. Cu, As, Te, Sn, Bi and Au represent the key metals of the high-sulfidation stage whereas the metal association Zn-Pb-Ag is typical for the intermediate-sulfidation stage. Based on fluid inclusion studies, the Capillitas deposit can be characterized by temperatures of ore formation mostly below 300 °C and low salinities (< 6 wt. % NaCl equivalent).
Baumstarkite is a new mineral found coating miargyrite from the San Genaro mine, Huancavelica Dep... more Baumstarkite is a new mineral found coating miargyrite from the San Genaro mine, Huancavelica Department, Peru. It is triclinic and the third naturally occurring modification of AgSbS 2 besides monoclinic miargyrite and cubic cuboargyrite. The composition is usually close to the ideal formula. However, some grains of baumstarkite show zoned lamellae with As contents up to 11.5 wt% and accords to Ag 3 (Sb,As) 2 SbS 6 . Baumstarkite is isotypic with aramayoite [end-member composition Ag 3 Sb 2 BiS 6 ; solid solutions require the extended formula Ag 3 Sb 2 (Bi,Sb)S 6 ]. Single-crystal Xray structure investigations were performed for baumstarkite [type locality, a = 7.766 , b = 8.322(2), c = 8.814(2) Å, a = 100.62(2), b = 104.03(2), g = 90.22(2)∞, Z = 2{Ag 3 Sb 3 S 6 }, space group P1 -, R1(F) = 0.057, wR 2 (F 2 ) = 0.128], aramayoite [Armonia mine, El Quevar, Argentinia: a = 7.813(2), b = 8.268(2), c = 8.880(2) Å, a = 100.32(2), b = 104.07(2), g = 90.18(2)∞, Z = 2{Ag 3 Sb 2 S 6 }, space group P1 -, R1(F) = 0.034, wR2(F 2 ) = 0.084], and miargyrite associated with baumstarkite type material [a = 12.862(3), b = 4.409(1), c = 13.218(3) Å, b = 98.48(2)∞, Z = 8{AgSbS 2 }, space group C2/c, R1(F) = 0.031, wR2(F 2 ) = 0.082].
Qualitative optical properties are described, and reflectance spectra provided, for cotype montbr... more Qualitative optical properties are described, and reflectance spectra provided, for cotype montbrayite, from the Robb Montbray mine, Quebec, together with the results of electron-microprobe analyses. The optical data are compared with data for all of the known gold telluride minglal5; microscope-spectrophotometry is found to be a useful technique to distinguish the different minerals. Attention is drawn to discrepancies between reflectance spectra measured with singleand double-beam microscopespectrophotometers.
Suredaite, ideally PbSnS 3 , is a new mineral species from the Pirquitas Ag-Sn deposit (Province ... more Suredaite, ideally PbSnS 3 , is a new mineral species from the Pirquitas Ag-Sn deposit (Province Jujuy, NW-Argentina). It was observed in symmetrically banded veins in the Oploca district, and is associated with sphalerite, arsenopyrite, pyrite-marcasite, cassiterite, cylindrite, franckeite, hocartite, rhodostannite, and various Ag-Sb and Ag-Bi sulfosalts in minor amounts. Suredaite occurs in layers up to 1 cm in thickness as aggregates of radially arranged tabular-prismatic (single) crystals, has a metallic lustre, and a dark grey streak. VHN 50 ranges between 18.2 and 20.6 (mean 19.6) GPa, the Mohs hardness is 2.5-3. It has perfect cleavages parallel to {001}, {101}, and {100}. The measured density varies between 5.54 and 5.88 g/cm 3 , D x was determined to be 5.615 g/cm 3 . In reflected plane-polarised light, it is white and is not perceptibly bireflectant or pleochroic. It lacks internal reflections and is weakly anisotropic with metallic blue, mauve to brown rotation tints. Specular reflectance percentages in air and in oil are tabulated from 400 to 700 nm and compared graphically with those for the type specimen of teallite, PbSnS 2 . Electron microprobe analyses showed suredaite to be chemically inhomogeneous with respect to the compositional variations (in wt%): Pb 42.3-48.5, Ag 0.3-1.1, Fe 0.3-1.0, As 0.2-2.1, Sn 27.7-30.2, S 23.1-24.7. The crystal structure determined from single-crystal X-ray diffraction data revealed orthorhombic symmetry [space group Pnma, Z = 4, a = 8.8221(3), b = 3.7728(3), c = 14.0076(3) Å; V = 466.23(4) Å 3 ]. The atomic arrangement is isostructural to the NH 4 CdCl 3 structure type which exists in a series of isotypic sulfides and selenide compounds. The suredaite structure, which is the natural analogue of synthetic PbSnS 3 , consists of columns of double-edge sharing octahedra running parallel to the b axis, which house the Sn atoms. These columns are linked by rods of eightfold-coordinated Pb atoms. On the basis of the structure determination, the empirically determined idealized formula follows a [8] (Pb, As,Ag, Sn) [6] (Sn,Fe)S 3 stoichiometry. Crystalchemical arguments suggest Ag possibly to occupy interstitial sites according to the alternative formula [4] (s,Ag) [8] (Pb, As, Sn) [6] (Sn,Fe) S 3 . The name of this new mineral species is in honor of R.J. Sureda Leston, head of the
Baumstarkite is a new mineral found coating miargyrite from the San Genaro mine, Huancavelica Dep... more Baumstarkite is a new mineral found coating miargyrite from the San Genaro mine, Huancavelica Department, Peru. It is triclinic and the third naturally occurring modification of AgSbS 2 besides monoclinic miargyrite and cubic cuboargyrite. The composition is usually close to the ideal formula. However, some grains of baumstarkite show zoned lamellae with As contents up to 11.5 wt% and accords to Ag 3 (Sb,As) 2 SbS 6 . Baumstarkite is isotypic with aramayoite [end-member composition Ag 3 Sb 2 BiS 6 ; solid solutions require the extended formula Ag 3 Sb 2 (Bi,Sb)S 6 ]. Single-crystal Xray structure investigations were performed for baumstarkite [type locality, a = 7.766 , b = 8.322(2), c = 8.814(2) Å, a = 100.62(2), b = 104.03(2), g = 90.22(2)∞, Z = 2{Ag 3 Sb 3 S 6 }, space group P1 -, R1(F) = 0.057, wR 2 (F 2 ) = 0.128], aramayoite [Armonia mine, El Quevar, Argentinia: a = 7.813(2), b = 8.268(2), c = 8.880(2) Å, a = 100.32(2), b = 104.07(2), g = 90.18(2)∞, Z = 2{Ag 3 Sb 2 S 6 }, space group P1 -, R1(F) = 0.034, wR2(F 2 ) = 0.084], and miargyrite associated with baumstarkite type material [a = 12.862(3), b = 4.409(1), c = 13.218(3) Å, b = 98.48(2)∞, Z = 8{AgSbS 2 }, space group C2/c, R1(F) = 0.031, wR2(F 2 ) = 0.082].
Germanium is enriched in several epithermal deposits of Bolivia and Argentina. Pb-Zn-Ag deposits ... more Germanium is enriched in several epithermal deposits of Bolivia and Argentina. Pb-Zn-Ag deposits of the Bolivian silver-tin belt may contain high-grade Ge mineralization. Ge is present as the mineral argyrodite, AgsGeS6, which is usually associated with a bonanza-grade silver mineralization composed of Ag-sulfosalts (pyrargyrite, stephanite, polybasite, diaphorite), native silver and acanthite. A significant anomaly of Ge was detected in Ag-enriched ore shoots of the Porco deposit. Ge also occurs in polymetallic and precious metal-bearing ore at Capillitas, Argentina. Ge is either bound to the mineral argyrodite, thus similar to the deposits in Bolivia, or present in supergene enriched copper ore of the La Rosario vein. The latter paragenesis is characterized by distinct Ge minerals such as putzite, catamarcaite, " Ge-stannoidite " (all of them represent new mineral species) and briartite which are associated with high-grade chalcocite-bornite ore. The Ge mineralization of Bolivia and Argentina was generated in an epithermal environment of either low-sulphidation (Ag-Zn-Pb) or high-sulphidation (Cu-As-Au-W) type.
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