The Canadian Mineralogist最新文献

{"title":"From Structure Topology to Chemical Composition. XXXI. Refinement of the Crystal Structure and Chemical Formula of Selivanovaite, NaFe3+Ti4(Si2O7)2O4(H2O)4, a Murmanite-Group (Seidozerite Supergroup) TS-Block Mineral from the Lovozero Massif, Kola Peninsula, Russia","authors":"E. Sokolova, Maxwell C. Day, F. Hawthorne, F. Cámara","doi":"10.3749/canmin.2100049","DOIUrl":"https://doi.org/10.3749/canmin.2100049","url":null,"abstract":"\u0000 Selivanovaite, ideally NaFe3+Ti4(Si2O7)2O4(H2O)4, is a murmanite-group (seidozerite supergroup) TS-block mineral from the Lovozero massif, Kola Peninsula, Russia. The crystal structure of selivanovaite was refined in space group C, a 10.524(6), b 13.815(6), c 12.213(14) Å, α 99.74(6), β 107.45(8), γ 90.15(10)°, V 1666.8(26) Å3, R1 = 21.40%. The previously given chemical analysis has been modified to better fit the crystal structure: Nb2O5 8.51, ZrO2 2.94, TiO2 31.96, SiO2 30.62, Al2O3 0.05, Fe2O3 5.08, FeO 3.23, MnO 3.36, CaO 2.14, MgO 0.75, Na2O 2.47, H2O 8.88, sum 99.99 wt.%; H2O was determined from structure-refinement results: H2O = 3.34 pfu, OH = 1.05 pfu. The empirical formula calculated on 22 O apfu is: (Na0.63Ca0.30Mn0.36)Σ1.29(Fe3+0.50Fe2+0.35)Σ0.85(Ti3.14Nb0.50Zr0.19Mg0.15Mn0.01Al0.01)Σ4.00Si3.99O22.00H7.73, Z = 4. The crystal structure of selivanovaite [basic structure type B1(MG)] is an array of TS blocks (Titanium Silicate) connected via hydrogen bonds. The TS block consists of HOH sheets (H = heteropolyhedral, O = octahedral) parallel to (001). In the O sheet, the Ti-dominant MO(1,2) sites, Na-dominant MO(3) site, and □-dominant MO(4) sites give ideally Na□Ti2pfu. In the H sheet, the Ti-dominant MH(1,2) sites, Fe3+-dominant AP(1) site, and vacant AP(2) sites give ideally Fe3+□Ti2pfu. The MH and AP(1) polyhedra and Si2O7 groups constitute the H sheet. The ideal structural formula of selivanovaite of the form AP2MH2MO4(Si2O7)2(XOM,A)4(XPM,A)4 is Fe3+□Ti2Na□Ti2(Si2O7)2O4(H2O)4. Selivanovaite is a Fe3+-bearing and OH-poor analogue of vigrishinite, ideally Zn□Ti2Na□Ti2(Si2O7)2O2O(OH)(H2O)4. Vigrishinite and selivanovaite are related by the following substitution: O(OH)–vig + H(Zn2+)vig ↔ O(O2–)sel + H(Fe3+)sel. Selivanovaite is a Fe3+-bearing and Na-poor analogue of murmanite, ideally Na2Ti2Na2Ti2(Si2O7)2O4(H2O)4. Murmanite and selivanovaite are related by the following substitution: O(Na+)mur + H(Na+2)mur ↔ O(□)sel + H(Fe3+)sel + H(□)sel. The doubling of the t1 and t2 translations of selivanovaite compared to those of murmanite is due to the ordering of Fe3+ and □ in the H sheet and Na and □ in the O sheet of selivanovaite.","PeriodicalId":134244,"journal":{"name":"The Canadian Mineralogist","volume":"18 23","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113941723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From Structure Topology to Chemical Composition. XXX. Refinement of the Crystal Structure and Chemical Formula of Shkatulkalite, Na2Nb2Na3Ti(Si2O7)2O2(FO)(H2O)4(H2O)3, a Lamprophyllite-Group (Seidozerite Supergroup) TS-Block Mineral from the Lovozero Massif, Kola Peninsula, Russia","authors":"E. Sokolova, Maxwell C. Day, F. Hawthorne, F. Cámara","doi":"10.3749/canmin.2100016","DOIUrl":"https://doi.org/10.3749/canmin.2100016","url":null,"abstract":"\u0000 Shkatulkalite, ideally Na5TiNb2(Si2O7)2O3F(H2O)7, is a lamprophyllite-group (seidozerite supergroup) TS-block mineral from the Lovozero massif, Kola Peninsula, Russia. The crystal structure of shkatulkalite was refined as triclinic, space group P, a 5.464(1), b 7.161(1), c 15.573(1) Å, α 90.00(3), β 95.75(3), γ 90.00(3)°, V 606.3(4) Å3, R1 = 7.26%. The previously given chemical analysis has been modified to better fit the crystal structure: Nb2O5 24.15, TiO2 11.35, SiO2 27.22, BaO 1.15, SrO 2.20, MnO 1.68, CaO 0.46, K2O 0.29, Na2O 14.78, H2O 15.27, F 1.61, O = F −0.68, sum 99.48 wt.%; H2O was determined from structure-refinement results. The empirical formula was calculated on 25.27 (O + F) apfu (in accord with the crystal structure): (Na1.40Sr0.19Ba0.07K0.05)Σ1.71(Na2.86Mn0.10Ca0.07)Σ3.03(Nb1.62Ti1.27Mn0.11)Σ3Si4.03O24.52H15.11F0.75, Z = 1. The ideal structural formula is as follows: Na2Nb2Na3Ti(Si2O7)2O2(FO)(H2O)4(H2O)3. The crystal structure of shkatulkalite [basic structure type B5(LG)] is a combination of a TS (titanium-silicate) block and an I (intermediate) block. The TS block consists of HOH sheets (H-heteropolyhedral, O-octahedral). The TS block exhibits linkage and stereochemistry typical for the lamprophyllite group where Ti (+ Nb + Fe3+ + Mg) = 3 apfu. The O sheet is composed of Ti-dominant MO(1) and Na-dominant MO(2,3) octahedra. In the H sheet in shkatulkalite, Si2O7 groups link to Nb-dominant MH octahedra. The AP site occurs in the plane of the H sheet and splits into AP(1) and AP(2) sites, occupied by Na at 70% and Sr (less Ba and K) at 11%. The I block consists of H2O groups. The I block of shkatulkalite is topologically identical to those in the derivative structures of kazanskyite and nechelyustovite. The structure of the lamprophyllite-group mineral shkatulkalite has a counterpart structure in the murmanite group (Ti = 4 apfu): kolskyite, ideally Na2CaTi4(Si2O7)2O4(H2O)7 [basic structure type B7(MG)]: the two structures have TS blocks of different topology and similar I blocks, mainly occupied by H2O groups.","PeriodicalId":134244,"journal":{"name":"The Canadian Mineralogist","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123919284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Crystal Structure of Malhmoodite from Custer, South Dakota, USA","authors":"Hexiong Yang, X. Gu, T. Loomis, R. Gibbs, R. Downs","doi":"10.3749/canmin.2100029","DOIUrl":"https://doi.org/10.3749/canmin.2100029","url":null,"abstract":"\u0000 An occurrence of malhmoodite, Fe2+Zr(PO4)2·4H2O, from the Scott's Rose Quartz mine, Custer County, South Dakota, USA, has been identified. It occurs as divergent groups of yellowish, flat-lying platy crystals on football-size masses of altered löllingite with scorodite, parasymplesite, karibibite, schneiderhöhnite, kahlerite, and zircon. An electron probe microanalysis of malhmoodite yielded an empirical formula (based on 12 O apfu) of Fe1.06(Zr1.10Hf0.03)Σ1.13[(P0.93As0.01)Σ0.94O4]2·4H2O.\u0000 Single-crystal X-ray structure analysis shows that malhmoodite is the Fe-analogue of zigrasite, MgZr(PO4)2·4H2O. Malhmoodite is triclinic with space group P and unit-cell parameters a = 5.31200(10), b = 9.3419(3), c = 9.7062(3) Å, α = 97.6111(13), β = 91.9796(11), γ = 90.3628(12)°, V = 477.10(2) Å3, Z = 2, in contrast to the previously reported monoclinic symmetry with space group P21/c and unit-cell parameters a = 9.12(2), b = 5.42(1), c = 19.17(2) Å, β = 94.8(1)°, V = 944.26 Å3, Z = 4. The crystal structure of malhmoodite is characterized by sheets composed of ZrO6 octahedra sharing all vertices with PO4 tetrahedra. These sheets are parallel to (001) and are joined together by the FeO2(H2O)4 octahedra. The structure determination of malhmoodite, along with that of zigrasite, warrants a re-investigation of synthetic compounds M2+Zr(PO4)2·4H2O (M = Mn, Ni, Co, Cu, or Zn) that have been assumed previously to be monoclinic.","PeriodicalId":134244,"journal":{"name":"The Canadian Mineralogist","volume":"2015 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132498559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crystal Structure of Tengchongite with a Revised Chemical Formula Ca(UO2)6(MoO4OH)2O2(OH)4·9H2O","authors":"Ting Li, Guang Fan, Xiangkun Ge, Tao Wang, Apeng Yu, Liumin Deng","doi":"10.3749/canmin.2000127","DOIUrl":"https://doi.org/10.3749/canmin.2000127","url":null,"abstract":"\u0000 Tengchongite, a uranyl molybdate mineral from Tengchong County, Yunnan Province, China, was originally described as orthorhombic, with space group A2122, unit-cell parameters a = 15.616(4) Å, b = 13.043(6) Å, c = 17.716(14) Å, V = 3608 Å3, and an ideal chemistry CaO·6UO2·2MO3·12H2O. Its ideal chemical formula is given as Ca(UO2)6(MoO4)2O5·12H2O in the current IMA-CNMNC List of Mineral Names. Tengchongite is the only mineral with a U:Mo ratio of 3:1, the second-highest ratio of all natural and synthetic uranyl molybdate materials, but its crystal structure remained undetermined until now. This study reports the structure determination of tengchongite from the type sample and a revision of its chemical formula to Ca(UO2)6(MoO4OH)2O2(OH)4·9H2O. Tengchongite is orthorhombic, with space group C2221, Z = 4, a = 13.0866(8) Å, b = 17.6794(12) Å, c = 15.6800(9) Å, and V = 3627.8(4) Å3. Its crystal structure was refined from single-crystal X-ray diffraction data to R1 = 0.0323 for 6055 unique observed reflections. The fundamental building blocks of the tengchongite structure are sheets consisting of six-membered clusters of edge-sharing UO7 pentagonal bipyramids, which are connected by sharing vertices among them, as well as edges and vertices with MoO5 trigonal bipyramids. These sheets, parallel to [010], are linked together by Ca2+ and H2O groups. Tengchongite represents a new type of structural connectivity between U- and Mo-polyhedra for uranyl molybdate minerals.","PeriodicalId":134244,"journal":{"name":"The Canadian Mineralogist","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126001130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Mineralogy of Pt-Fe Alloys and Phase Relations in the Pt–Fe Binary System","authors":"L. Cabri, T. Oberthür, D. Schumann","doi":"10.3749/canmin.2100060","DOIUrl":"https://doi.org/10.3749/canmin.2100060","url":null,"abstract":"\u0000 A revised Pt–Fe phase diagram is proposed to replace those used in the materials science literature (e.g., Okamoto 2004), and to improve the one of Cabri & Feather (1975) by adding high-temperature phase equilibria data published in the mineralogical literature. The projected solid-solution fields at room temperature in the pure Pt–Fe system lie at the following approximate compositions: for γ(Pt,Fe) from Pt to Pt0.78Fe0.22, for Pt3Fe from Pt3.04Fe0.96 to Pt2.64Fe1.36, for PtFe from Pt1.16Fe0.84 to Pt0.67Fe0.33, and for PtFe3 from Pt1.26Fe2.94 to Pt0.68Fe3.32. The phase relations and phase boundaries are discussed and evaluated for Pt-Fe alloys occurring in pristine intrusive rocks and ores as well as in eluvial and placer deposits derived from the former by physical and chemical weathering over long periods of geologic time. In spite of the variable concentrations of minor and trace elements, the natural Pt-Fe alloy minerals correlate well with phase relations in the pure Pt–Fe binary system.","PeriodicalId":134244,"journal":{"name":"The Canadian Mineralogist","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115902019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bonding Between the Decavanadate Polyanion and the Interstitial Complex in Pascoite-Family Minerals","authors":"F. Hawthorne, John M. Hughes, M. Cooper, A. Kampf","doi":"10.3749/canmin.2100051","DOIUrl":"https://doi.org/10.3749/canmin.2100051","url":null,"abstract":"\u0000 The decavanadate isopolyanion, [V10O28]6–, is a constituent of pascoite-family vanadate minerals and synthetic materials, and both protonated, [HxV10O28](6–x)–, and mixed-valence, [V4+xV5+10–x)O28](6+x)–, varieties have been described. Here we analyze the interaction between the interstitial complex and the decavanadate structural unit using the principle of correspondence of Lewis acidity-basicity. The Lewis base strengths of the decavanadate polyanions vary from 0.054 to 0.154 vu and [V10O28] structures can form from the simple cations Cs+, Rb+, K+, Tl+, and Na+; simple cations with higher Lewis acidities are too acid to form structures. Cations may bond to transformer (H2O) groups to form polyatomic cations that have lower Lewis acidities than the corresponding simple cation. The occurrence of the polyatomic cation {(V5+O2)Al10(OH)20(H2O)18}11+ in caseyite shows the potential for decavanadate phases to incorporate large heteropolycations into their structures. In turn, this suggests that the [V10O28] polyanions may be used to induce co-crystallization of large aqueous polyatomic cations, thus facilitating their structural characterization. There is an inverse relation between the amount of (H2O) in the interstitial complex and the number of bonds between interstitial simple cations and the O2– ions of the vanadate units, and there is a strong correlation between the unit-cell volume per decavanadate unit and the number of (H2O) groups.","PeriodicalId":134244,"journal":{"name":"The Canadian Mineralogist","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122080747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrographic and Geochemical Characteristics Associated with Felsic Xenolith Assimilation in Kimberlite","authors":"Sofya Niyazova, M. Kopylova, M. Gaudet, A. De Stefano","doi":"10.3749/canmin.2000107","DOIUrl":"https://doi.org/10.3749/canmin.2000107","url":null,"abstract":"\u0000 Assimilation of country rock xenoliths by the host kimberlite can result in the development of concentric reaction zones within the xenoliths and a reaction halo in the surrounding contaminated kimberlite. Petrographic and geochemical changes across the reaction zones in the xenoliths and the host kimberlite were studied using samples with different kimberlite textures and contrasting xenolith abundances from the Renard 65 kimberlite pipe. The pipe, infilled by Kimberley-type pyroclastic (KPK) and hypabyssal kimberlite (HK) and kimberlite with transitional textures, was emplaced into granitoid and gneisses of the Superior Craton. Using samples of zoned, medium-sized xenoliths of both types, mineralogical and geochemical data were collected across xenolith-to-kimberlite profiles and contrasted with those of fresh unreacted country rock and hypabyssal kimberlite. The original mineralogy of the unreacted xenoliths (potassium feldspar-plagioclase-quartz-biotite in granitoid and plagioclase-quartz-biotite-orthopyroxene in gneiss) is replaced by prehnite, pectolite, and diopside. In the kimberlite halo, olivine is completely serpentinized and diopside and late phlogopite crystallized in the groundmass. The xenoliths show the progressive degrees of reaction, textural modification, and mineral replacement in the sequence of kimberlite units KPK — transitional KPK — transitional HK. The higher degree of reaction observed in the HK-hosted xenoliths as compared to the KPK-hosted xenoliths in this study and elsewhere may partly relate to higher temperatures in xenoliths included in an HK melt. The correlation between the degree of reaction and the kimberlite textures suggests that the reactions are specific to and occur within each emplaced batch of magma and cannot result from external post-emplacement processes that should obliterate the textural differences across the kimberlite units. Xenolith assimilation may have started in the melt, as suggested by the textures in the xenoliths and the surrounding halos and proceeded in the subsolidus. Elevated CaO at the kimberlite-xenolith contact appears to be an important factor in producing the concentric mineralogical zoning in assimilated xenoliths.","PeriodicalId":134244,"journal":{"name":"The Canadian Mineralogist","volume":"123 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127065645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The origin of gem spodumene in the Hamadan Pegmatite, Alvand Plutonic Complex, western Iran","authors":"Rasoul Sheikhi Gheshlaghi, M. Ghorbani, A. Sepahi, R. Deevsalar, K. Nakashima, R. Shinjo","doi":"10.3749/canmin.2000087","DOIUrl":"https://doi.org/10.3749/canmin.2000087","url":null,"abstract":"\u0000 Pegmatite bodies with a simple mineral composition are widespread within the Sanandaj-Sirjan Zone (SaSiZ), Zagros Orogen, Iran; however, gem-bearing pegmatite bodies are rare. There is a pegmatitic vein within the Hamadan garnet (± andalusite ± staurolite) schist adjacent to the Alvand Plutonic Complex (APC), south of Hamedan city (western Iran), in which large crystals of gem spodumene occur together with quartz, amazonite, beryl, tourmaline, and apatite. This spodumene-bearing pegmatite consists of four major zones with slightly different mineral compositions from the border to the core. The wall zone of quartz-rich granitoid and the intermediate zone of alkali granite have trondhjemitic compositions near the quartzolitic gem-bearing core zone. All parts of the vein are peraluminous in composition and exhibit S-type affinity. Two types of spodumene which have been distinguished in the core zone are colorless to very pale yellow and pink, transparent with vitreous luster and inclusion-free (eye clean) under 10× magnification. The different color in these minerals can be attributed to the slightly different chemical compositions, particularly lower Fe/Mn ratios in the pink material. The δ7Li values of the spodumene (+5.58 to +6.57‰) are indicative of the incorporation of middle continental crustal components in their genesis. Change in the mineral assemblage from tourmaline-bearing in the intermediate zone to spodumene + tourmaline in the core zone of the spodumene-bearing pegmatite is consistent with increasing lithium content from the wall zone to the core. Petrographic, geochemical, and isotopic data indicate that partial melting of middle-crustal Al-rich metapelitic source was followed by fractional crystallization to generate these rocks. In this concern, the required Li for the crystallization of spodumene was probably supplied by the breakdown of staurolite of the Hamadan schist and/or subsequent fractional crystallization of the parent magma. The results also demonstrate that the regional tectonic regime exerts a primary control on the occurrence and emplacement of the miarolitic pegmatite in the upper crust and the formation of gem spodumene during late-stage magmatic activities.","PeriodicalId":134244,"journal":{"name":"The Canadian Mineralogist","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128610184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A proposed new mineralogical classification system for granitic pegmatites","authors":"M. Wise, A. Müller, W. Simmons","doi":"10.3749/canmin.1800006","DOIUrl":"https://doi.org/10.3749/canmin.1800006","url":null,"abstract":"\u0000 The current classification of granitic pegmatites, originally introduced by Černý (1991a), has been the accepted system for grouping pegmatites of diverse mineralogy and chemistry for nearly three decades. Despite its general acceptance, several issues have been highlighted (Müller et al. 2022) which have imposed some limitations on its use and therefore necessitated the need to reevaluate its methodology. A new classification for granitic pegmatites is proposed in an attempt to be more inclusive of pegmatite types omitted in previous classification schemes. The new approach utilizes a more comprehensive suite of accessory minerals and defines three pegmatite groups which are genetically related to granite plutons and the anatexis of metaigneous and metasedimentary protoliths. Pegmatites belonging to Groups 1 and 2 are generated from the residual melts of S-, A-, and I-type granite magmatism (RGM) as well as being direct products of anatexis (DPA), whereas Group 3 pegmatites are only derived by anatexis.","PeriodicalId":134244,"journal":{"name":"The Canadian Mineralogist","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130277550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Macro- to nanoscale mineral relationships in surficial cobalt-arsenic-bearing mine tailings of the Cobalt Mining Camp, Northeastern Ontario, Canada","authors":"Brittaney Courchesne, Michael Schindler, A. Lussier, N. Mykytczuk","doi":"10.3749/canmin.2000103","DOIUrl":"https://doi.org/10.3749/canmin.2000103","url":null,"abstract":"\u0000 Arsenates, which correspond to the majority of known arsenic (As)-bearing minerals, control the mobilization of As in contaminated soils, sediments, and fluvial environments as well as in tailings and mine waste piles. Additionally, arsenate-bearing Fe-(hydr)oxides are of particular significance for the control of As mobility, as they are among the most thermodynamically stable minerals under near-neutral to alkaline pH conditions. However, in the surficial (upper 30 cm) alkaline mine tailings at the Cobalt Mining Camp in Northeastern Ontario, Canada, these phases only occur in trace amounts. This study attempts to understand this unusual mineralogical feature through an investigation of the relationships between nano- and macroscale mineralogical and geochemical features at two tailings sites (A and B) at the Cobalt Mining Camp. Sixty samples from two depth profiles (0–30 cm; i.e., one sample per centimeter) were collected at the two sites, analyzed for their major and minor chemical elements, and characterized for their mineralogical composition at the nano- to centimeter scale. The tailings material at both sites is predominantly composed of minerals of the amphibole, chlorite, and feldspar groups, as well as carbonates (calcite and dolomite). Minor phases are Co-Fe-Ni-Zn-sulfarsenides and -arsenates. The tailings material at site B contains, on average, higher concentrations of As, Co, Sb, and Zn and lower concentrations of Fe than the material at site A. Secondary (scanning electron microscope) and transmission electron microscopy studies indicate that the alteration of primary sulfarsenides to secondary arsenates may proceed in the following sequence: (1) the formation of Fe-hydroxide and -arsenate mineral surface coatings on sulfarsenides; (2) the downward mobilization of Co-Ni-Zn-arsenate and (FeOHCO3)aq species; (3) replacement of earlier-formed scorodite by Co-Ni-Zn-arsenates; (4) the precipitation of Co-Ni-Zn-arsenates on the surfaces of silicates; and (5) neoformation of Fe-rich hydroxy-interlayered minerals at greater depth, partly replacing earlier-formed Co-Ni-Zn-arsenates. These processes result in layers enriched in As, Co, Sb, and Zn (increase in Co#) and enriched and depleted in Fe (increase and decrease in Fe#) in tailings material at both sites. The TEM studies further indicate that Co-Ni-Zn-arsenates precipitate initially as nanoparticles on the surface of scorodite and detrital silicates and subsequently coarsen through Oswald ripening. The mineralogical-geochemical features depicted in this study provide a better understanding of the geochemical behavior of Co, Fe, and As in alkaline tailings and may assist in the interpretation of mineral-microbial community associations and the development of effective bioleaching strategies for the strategic element cobalt.","PeriodicalId":134244,"journal":{"name":"The Canadian Mineralogist","volume":"159 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116405910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}