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REVISION 1 an Insight at the Inverse Transformation of Realgar Altered By
REVISION 1 An insight at the inverse transformation of realgar altered by light Giovanni Pratesi1,2 and Matteo Zoppi1* 1Museo di Storia Naturale - Sezione Mineralogia e Litologia, Università di Firenze, via La Pira 4, I- 50121 Firenze, Italy. 2Dipartimento di Scienze della Terra, Università di Firenze, via La Pira 4, I-50121 Firenze, Italy. * E-mail: [email protected] ABSTRACT The light-induced alteration of realgar and β-As4S4 is a well known phenomenon but still displays interesting aspects not completely explained. In the transformation from realgar to pararealgar the molecule As4S4 undergoes a structural modification, and ever since the initial studies two important issues have been highlighted: the influence of the oxygen and the reversibility of the process. The previous study on the reversibility of the altered β-As4S4 points out that this polymorph exhibits a dual behaviour. When the light-induced alteration occurs with the presence of the air, pararealgar and arsenolite, along with amorphous material, are the products, while if the air is not present β-As4S4 turns completely into pararealgar. Moreover, when annealing the altered material in the realgar stability fields (220 °C), in the first case pararealgar and amorphous material turn into stoichiometric alacranite, while in the second case the alteration is completely reversible. Similarly, the present study focuses the attention on the question if realgar, when altered by means of the light and when annealed, might behave as β-As4S4 does. These results display that the phenomenon is more complex. The alteration of realgar with the presence of the air yields pararealgar along with arsenolite, a small quantity of uzonite and amorphous material, and when the air is not present pararealgar is the only product. -
Silver Enrichment in the San Juan Mountains, Colorado
SILVER ENRICHMENT IN THE SAN JUAN MOUNTAINS, COLORADO. By EDSON S. BASTIN. INTRODUCTION. The following report forms part of a topical study of the enrich ment of silver ores begun by the writer under the auspices of the United States Geological Survey in 1913. Two reports embodying the results obtained at Tonopah, Nev.,1 and at the Comstock lode, Virginia City, Nev.,2 have previously been published. It was recognized in advance that a topical study carried on by a single investigator in many districts must of necessity be less com prehensive than the results gleaned more slowly by many investi gators in the course of regional surveys of the usual types; on the other hand the advances made in the study of a particular topic in one district would aid in the study of the same topic in the next. In particular it was desired to apply methods of microscopic study of polished specimens to the ores of many camps that had been rich silver producers but had not been studied geologically since such methods of study were perfected. If the results here reported appear to be fragmentary and to lack completeness according to the standards of a regional report, it must be remembered that for each district only such information could be used as was readily obtainable in the course of a very brief field visit. The results in so far as they show a primary origin for the silver minerals in many ores appear amply to justify the work in the encouragement which they offer to deep mining, irrespective of more purely scientific results. -
Mineral Zoning and Geochemistry of Epithermal Polymetallic Zn-Pb-Ag-Cu-Bi Mineralization at Cerro De Pasco, Peru
Article Mineral zoning and geochemistry of epithermal polymetallic Zn-Pb-Ag-Cu-Bi mineralization at Cerro de Pasco, Peru BAUMGARTNER, Regine, FONTBOTÉ, Lluís, VENNEMANN, Torsten Abstract The large Cerro de Pasco Cordilleran base metal deposit in central Peru is located on the eastern margin of a middle Miocene diatreme-dome complex and comprises two mineralization stages. The first stage consists of a large pyrite-quartz body replacing Lower Mesozoic Pucará carbonate rocks and, to a lesser extent, diatreme breccia. This body is composed of pyrite with pyrrhotite inclusions, quartz, and black and red chalcedony (containing hypogene hematite). At the contact with the pyrite-quartz body, the diatreme breccia is altered to pyrite-quartz-sericite-pyrite. This body was, in part, replaced by pipelike pyrrhotite bodies zoned outward to carbonate-replacement Zn-Pb ores bearing Fe-rich sphalerite (up to 24 mol % FeS). The second mineralization stage is partly superimposed on the first and consists of zoned east-west–trending Cu-Ag-(Au-Zn-Pb) enargite-pyrite veins hosted in the diatreme breccia in the western part of the deposit and well-zoned Zn-Pb-(Bi-Ag-Cu) carbonate-replacement orebodies; in both cases, sphalerite is Fe poor and the inner parts of the orebodies show typically advanced argillic alteration [...] Reference BAUMGARTNER, Regine, FONTBOTÉ, Lluís, VENNEMANN, Torsten. Mineral zoning and geochemistry of epithermal polymetallic Zn-Pb-Ag-Cu-Bi mineralization at Cerro de Pasco, Peru. Economic Geology, 2008, vol. 103, p. 493-537 DOI : 10.2113/gsecongeo.103.3.493 Available at: http://archive-ouverte.unige.ch/unige:21616 Disclaimer: layout of this document may differ from the published version. -
Silver Mineralization at Sark's Hope Mine, Sark, Channel Islands
MINERALOGICAL MAGAZINE, DECEMBER 1983, VOL. 47, PP. 539-45 Silver mineralization at Sark's Hope mine, Sark, Channel Islands R. A. IXER Department of Geological Sciences, University of Aston in Birmingham, Gosta Green, Birmingham B4 7ET AND C. J. STANLEY Department of Mineralogy, British Museum (Natural History), Cromwell Road, South Kensington, London SW7 5BD ABSTRACT. Sark's Hope silver lead lode, which was The lead-silver-bearingvein, 'Sark's Hope Silver- mined during the 1830s and 1840s cuts a Late Precambrian Lead lode', cuts a foliated hornblende granite of granite at the southernmost point of the island of Sark. Late Precambrian age (Sutton and Watson, 1957). The primary ore assemblageis pyrite, galena,chalcopyrite, Although there is little trace of the vein today, tennantite, tetrahedrite, sphalerite, marcasite, arseno- with the outcrop workings being mostly obscured pyrite, pyrrhotine, bravoite, enargite, and the silver minerals pyrargyrite, pearceite, polybasite, and acanthite. by a thick cover of vegetation, the early accounts Gangue minerals are hematitic quartz, calcite, and illite. describe it as 0.4 to 2.5 m in width, more than 600 m Alteration products include chalcosine, covelline, blau- in length, oriented 028-037 ~ and dipping at 65-85 ~ bleibender covelline,limonite, malachite, azurite, cerussite, to the northwest. and anglesite. The generalized paragenesis is of early Fe, Small amounts of in situ ore were obtained from Co, Ni, As, and S species and later minerals of Pb, Cu, Ag, the poorly exposed and weathered parts of the vein Zn, Fe, As, Sb, and S. The earliest alteration products at the southwestern end, but most of our specimens are copper sulphides; these are followed by lead and were collected from the spoil tips, in particular from copper carbonates and sulphates, and hydrated iron and Le Pelley's shaft tip at the northeastern end of the manganese oxides. -
STRONG and WEAK INTERLAYER INTERACTIONS of TWO-DIMENSIONAL MATERIALS and THEIR ASSEMBLIES Tyler William Farnsworth a Dissertati
STRONG AND WEAK INTERLAYER INTERACTIONS OF TWO-DIMENSIONAL MATERIALS AND THEIR ASSEMBLIES Tyler William Farnsworth A dissertation submitted to the faculty at the University of North Carolina at Chapel Hill in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry. Chapel Hill 2018 Approved by: Scott C. Warren James F. Cahoon Wei You Joanna M. Atkin Matthew K. Brennaman © 2018 Tyler William Farnsworth ALL RIGHTS RESERVED ii ABSTRACT Tyler William Farnsworth: Strong and weak interlayer interactions of two-dimensional materials and their assemblies (Under the direction of Scott C. Warren) The ability to control the properties of a macroscopic material through systematic modification of its component parts is a central theme in materials science. This concept is exemplified by the assembly of quantum dots into 3D solids, but the application of similar design principles to other quantum-confined systems, namely 2D materials, remains largely unexplored. Here I demonstrate that solution-processed 2D semiconductors retain their quantum-confined properties even when assembled into electrically conductive, thick films. Structural investigations show how this behavior is caused by turbostratic disorder and interlayer adsorbates, which weaken interlayer interactions and allow access to a quantum- confined but electronically coupled state. I generalize these findings to use a variety of 2D building blocks to create electrically conductive 3D solids with virtually any band gap. I next introduce a strategy for discovering new 2D materials. Previous efforts to identify novel 2D materials were limited to van der Waals layered materials, but I demonstrate that layered crystals with strong interlayer interactions can be exfoliated into few-layer or monolayer materials. -
LIGHT-INDUCED CHANGES in MOLECULAR ARSENIC SULFIDES Different Steps of the Light Treatment
American Mineralogist, Volume 91, pages 1323–1330, 2006 Light-induced changes in molecular arsenic sulÞ des: State of the art and new evidence by single-crystal X-ray diffraction PAOLA BONAZZI,* LUCA BINDI, GIOVANNI PRATESI, AND SILVIO MENCHETTI Dipartimento di Scienze della Terra, Università di Firenze, via La Pira 4, I-50121 Firenze, Italy ABSTRACT β Light-induced structural changes in single crystals belonging to the -As4S4-As8S9 series and in a β crystal of synthetic -As4S3 were monitored step by step by determining the unit-cell dimensions. A marked increase of unit-cell volume as a function of exposure time was observed for all the crystals β belonging to the -As4S4-As8S9 series except for stoichiometric alacranite (As8S9). No signiÞ cant change β upon long exposures to light was observed for the synthetic -As4S3 crystal. Crystal structure reÞ ne- ments were carried out for crystals with different composition at selected steps of the light-induced process. The structural results clearly showed that the percentage of the As4S5 molecule in the structure increases when a crystal is exposed to light. Therefore, the increment of the unit-cell volume induced by light exposure appears to be related to a random replacement of As4S5 for As4S4 in the structure → according to the reaction 5As4S4 + 3O2 4As4S5 + 2As2O3. The results obtained in the present study combined with a critical review of data previously published indicate that the As4S4 molecule is able to incorporate sulfur to convert to As4S5 upon exposure to light, whereas either As4S3 or As4S5 mol- ecules do not go undergo any modiÞ cation. -
Uytenbogaardtite, a New Silver.Gold Sulfide
Carwdian Mineralogist Vol. 16, pp. 651-657 (1978) UYTENBOGAARDTITE,A NEW SILVER.GOLDSULFIDE M. D. BARTON{' Department ol Geological Sciences,Vireinia Polytechnic lttstitute and State University, Blacksburg,Virsinia 24061, U.S-4. C. KIEF"T NetherlandsOrganization for the Advancernentof Pure Research(ZWO)' Amsterdam' The Netherlands E. A. J. BURKE Institute lor the Earth Sciences,Free Uniyersity, Amsterdam 11, The Netherlands I. S. OEN GeoloeicalInstitute, University of Arnsterdam,Amsterdam, The Netherlands ABsrRAcr genberg), Altai (J.R.S.S.). C'est un min6ral t6trago' ia, ri'zz ou.P41, a 9.76, c 9.784. (Comstock); - D(calc) Uytenbogaardtite, Aga,AuSz,occurs with acanthite, a 9.68, c 9.814 Cfambang Sawah); Z 8; (Iambang I-es raies electrum and quartz in specimens from Tambang 8.34 (Comstock), 8.45 Sawah). plus 2.71(10) Sawah, Benkoelen district, Sumatra, Indonesia, the de diffraction-X les lntenses sont (421). compG' Comstock lode, Storey County, Nevada, U.S.A. (203), 2.60(9) (321) et 2.l2LQ) ks par proches de and Smeinogorski (Schlangenberg), Altai, U.S.S.R. sitions obtenues analyse sont quoique de Comstock The mineral is tetragonal, P4r22 or l4r a 9.76, Ag:AuSz, l'ufienbogaardtite jusqu'i (wids) Ces donn6es c 9.784. (Comstocklode), a 9.68, c 9.81A Cfambang contienne 4Vo de cuivre. basse- Sawah), Z - 8; D(calc) - 8.34 g/cm3 (Comstock montrent que I'uytenbogaardtite et la forme En lu- lode), 8.45 g/cma Sawah). The strongest temp6rature de Ag*AuSz sont identiques. Clambang pl6ochroique, de gris- X-ray powder diffraction lines are 2.71(L0) (2O3), midre r6fl6chie, le min6ral est gris-blanc l'air, et d'un 2.60(9) (321), 2.124(7\ (421). -
Smithite Agass2 C 2001-2005 Mineral Data Publishing, Version 1
Smithite AgAsS2 c 2001-2005 Mineral Data Publishing, version 1 Crystal Data: Monoclinic. Point Group: 2/m. Crystals commonly equant, {100}, {001}, {111}, {111}, and a dozen other forms; also tabular on {100}, to 3 mm; pseudohexagonal. Physical Properties: Cleavage: Perfect on {100}. Fracture: Conchoidal. Tenacity: Brittle. Hardness = 1.5–2 VHN = n.d. D(meas.) = 4.88 D(calc.) = 4.926 Optical Properties: Transparent; becoming opaque on exposure to light, then translucent in thin splinters. Color: Scarlet, vermilion, pink; becoming red-orange on exposure to light. Streak: Vermilion. Luster: Adamantine. Optical Class: Biaxial (–). Pleochroism: Slight in transmitted light. Orientation: Y = b; Z ∧ c = 6.5◦. Dispersion: Strong. n = 3.27(9) 2V(meas.) = ∼65◦ R1–R2: (400) 40.7–44.0, (420) 40.0–43.2, (440) 39.3–42.4, (460) 38.7–41.5, (480) 37.9–40.4, (500) 37.0–39.2, (520) 36.0–38.0, (540) 35.0–36.6, (560) 33.8–35.4, (580) 32.7–34.7, (600) 32.0–34.0, (620) 31.4–33.4, (640) 31.0–32.9, (660) 30.6–32.4, (680) 30.4–31.8, (700) 30.1–31.4 Cell Data: Space Group: A2/a. a = 17.23 b = 7.78 c = 15.19 β = 101◦120 Z=24 X-ray Powder Pattern: Synthetic. 2.82 (100), 3.21 (80), 2.72 (60), 1.953 (50), 1.701 (40), 1.661 (40), 1.608 (40) Chemistry: (1) (2) Ag 43.9 43.69 As 28.9 30.34 Sb 0.4 S 26.0 25.97 Total 99.2 100.00 (1) Binntal, Switzerland. -
Internal Vein Texture and Vein Evolution of the Epithermal Shila-Paula District, Southern Peru
Internal vein texture and vein evolution of the epithermal Shila-Paula district, southern Peru. Alain Chauvet, Laurent Bailly, Anne-Sylvie André-Mayer, Patrick Monié, Daniel Cassard, Fernando Llosa Tajada, Juan Rosas Vargas, Johann Tuduri To cite this version: Alain Chauvet, Laurent Bailly, Anne-Sylvie André-Mayer, Patrick Monié, Daniel Cassard, et al.. Internal vein texture and vein evolution of the epithermal Shila-Paula district, southern Peru.. Min- eralium Deposita, Spinger, 2006, 41, pp.387-410. 10.1007/s00126-006-0068-4. hal-00087435 HAL Id: hal-00087435 https://hal.archives-ouvertes.fr/hal-00087435 Submitted on 17 Jan 2007 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Internal vein texture and vein evolution of the epithermal Shila-Paula district, southern Peru Alain Chauvet1, 6 , Laurent Bailly2, Anne-Sylvie André3, Patrick Monié1, Daniel Cassard2, Fernando Llosa Tajada4, Juan Rosas Vargas4 and Johann Tuduri5 (1) UMR 5573, ISTEEM, University of Montpellier II, cc. 60, F-34095 Montpellier Cedex 5, France (2) REM, BRGM, BP 6009, F-45060 Orléans Cedex 2, France (3) UMR 7566, G2R, University Henri Poincaré, BP 239, F-54506 Vandœuvre-lès-Nancy Cedex, France (4) CEDIMIN S.A.C., Luis N. -
Pararealgar and Alacranite from the Nishinomaki Mine, Gunma Prefecture, Japan
Bull. Natn. Sci. Mus., Tokyo, Ser. C, 31, pp. 1–6, December 22, 2005 Pararealgar and Alacranite from the Nishinomaki Mine, Gunma Prefecture, Japan Satoshi Matsubara and Ritsuro Miyawaki Department of Geology and Paleontology, National Science Museum, 3–23–1, Hyakunin-cho, Shinjuku, Tokyo 169–0073, Japan Abstract Pararealgar and alacranite are found in the arsenic ore from the Nishinomaki mine, Gunma Prefecture, Japan. The unit cell parameters calculated by powder X-ray diffraction data are aϭ9.925(2), bϭ9.695(2), cϭ8.504(2) Å, bϭ97.1(1)° for pararealgar, and aϭ9.941(2), bϭ 9.398(2), cϭ8.910(2) Å, bϭ102.0(1)° for alacranite. Both minerals are yellow with resinous lus- ter, and often occur as mixture on the surface of realgar. They may be formed secondarily under the exposing of realgar by sunlight. Key words : pararealgar, alacranite, realgar, Nishinomaki mine. Introduction ognized as pararealgar (Strunz and Nickel, During the examination of the Sakurai Mineral 2001). Collection, we recognized the specimen from the The a-phase associated with pararealgar from Nishinomaki mine labeled as pararealgar by late the original localities is corresponding to the Dr. K. Sakurai. As the occurrence of pararealgar high-temperature AsS synthesized by Roland has not been known in Japan, we checked it by (1972). The powder X-ray diffraction data close- the powder X-ray diffraction method to confirm ly resemble alacranite, which was named for the whether the label was correct or not. The result first locality, Mina Alacrán, Pampa Larga, Chile of experiment revealed that the examined materi- (Clark, 1970), by Popova et al. -
Wakabayashilite (As, Sb)11S18 C 2001-2005 Mineral Data Publishing, Version 1
Wakabayashilite (As, Sb)11S18 c 2001-2005 Mineral Data Publishing, version 1 Crystal Data: Monoclinic, pseudohexagonal. Point Group: 2or2/m. As fibers elongated k [010], up to 2 cm long, or as prisms. Physical Properties: Cleavage: {100}, {010}, {101}, perfect. Tenacity: Flexible. Hardness = ∼1.5 VHN = n.d. D(meas.) = 3.96 D(calc.) = 4.06 Optical Properties: Translucent. Color: Golden to lemon-yellow, with golden yellow internal reflections. Streak: Orange-yellow. Luster: Silky (for fibrous aggregates) to resinous. Anisotropism: Weak. Pleochroism: Strong. R: (400) 28.4, (420) 27.8, (440) 27.2, (460) 26.0, (480) 24.5, (500) 23.3, (520) 22.5, (540) 22.0, (560) 21.8, (580) 21.6, (600) 21.6, (620) 21.5, (640) 21.4, (660) 21.3, (680) 21.2, (700) 21.2 Cell Data: Space Group: P 21 or P 21/m; P 63/mmc (pseudocell). a = 29.128 b = 6.480 c = 29.128 β = 120.0◦ Z = [8] X-ray Powder Pattern: White Caps mine, Nevada, USA. 6.28 (100), 3.488 (80), 4.78 (70), 3.239 (40), 3.078 (40), 2.423 (40), 1.590 (40) Chemistry: (1) (2) As 52.3 54.5 Sb 8.3 5.7 S 39.0 39.5 Total 99.6 99.7 (1–2) White Caps mine, Nevada, USA; by electron microprobe. Occurrence: As fibers in druses of quartz or embedded in calcite. Association: Realgar, orpiment, stibnite, pyrite (Nishinomaki mine, Japan); realgar, orpiment, calcite (White Caps mine, Nevada, USA); chabourn´eite,pierrotite, parapierrotite, stibnite, pyrite, sphalerite, twinnite, zinkenite, madocite, andorite, smithite, laffittite, routhierite, aktashite, realgar, orpiment (Jas Roux, France). -
THE PEARCEITE and POLYBASITE SERIES1 H. T. H.R.R.R., Department
THE AMERICAN MINERALOGIST, VOL .52,SEPTEMBER OCTOBER, 1967 THE PEARCEITE AND POLYBASITE SERIES1 H. T. H.r.r.r.,Department of Geologyand, Geophysics, Univers,ity of M'innesota, M inneap ol,is, M innesola. Ansrnlcr Experimental study of the phasespearceite (Ag, Cu)5 AszSnand polybasite (Ag, Cu)a SbrSr has shown that copper is an essential component and that these phases are end mem- bers of two distinct series: pearceite-antimonpearceiteand polybasite-arsenpolybasite. Synthetic arsenpolybasite is homogeneous over a compositional interval which extends from 3.0 to 5 2 weight percent copper at 200'C. Its antimony analog, polybasite, is stable from 3.1 to 7.6 weight percent copper at 200'C. Synthetic pearceite is homogeneousfrom 5.5 to 19.7 weight percent copper at 200'C; whereas, its antimony analog is homogeneous from 7 9 to 19.2 weight percent copper at 200'C. A narrow two-phase field separates the two solid solution series. At about 360oC arsenpolybasite inverts to a high temperature polymorph, X-arsenpolybasite. The compositional limits of copper for the two synthetic series corresponds with that found in natural material. INtnooucrroN Pearceite and polvbasite, with similar pseudohexagonalor monoclinic form and similar composition,8(Ag, Cu)zS'(As, Sb)zSaand 8(Ag, Cu)zS .(Sb, As)253,have generallybeen regardedas the arsenicand antimony end-members respectively, of a single solid solution series. Copper re- places silver in considerableand varying amounts in both minerals, and in polybasitethere mav alsobe substantialreplacement of antimony by arsenic. Although most of the specific properties of polybasite and pearceite are known, there are still somegaps and uncertainties in the descriptions.