Abstract Corundum with inclusions of enigmatic super-reduced minerals was found in mineral separates received as a result of alluvial sediment exploration near Mt Carmel, Israel by the Shefa Yamim Company. This corundum, registered as ‘Carmel sapphireTM’, has been an object of numerous publications by W. Griffin's scientific team, in which they propose a questionable hypothesis of sapphire formation at the crust–mantle boundary with the participation of CH4+H2 fluids. Typically the Carmel sapphire is in small fragments of breccia with white cement, which in the opinion of Griffin et al. is a carbonate-cemented volcanic ash. Our investigation of the ‘white breccia’ showed that it consists of unsorted angular fragments of Carmel sapphire from ~1 μm to 7 mm in size cemented by aluminium hydroxides (bauxite) and is a waste product of the fused alumina process, i.e. it has an anthropogenic origin. Phases typical for slags of fused alumina production and metallurgical slags were identified in the ‘white breccia’. Carmel sapphire has numerous microscopic spherical inclusions of Si–Fe alloy indicating that the removal of Si and Fe from the corundum melt occurred at a temperature >2000°С. Osbornite, TiN, from Carmel sapphire has a chemical zonation characteristic of osbornite from fused alumina with enrichment of central zones in carbon. Comparison of the growth heterogeneity of Carmel sapphire and ‘electrocorundum’ indicates that the crystallisation of the corundum melt proceeded in a similar way. Unfortunately, in the case of Carmel sapphire from the Carmel locality, the contamination of geological samples with anthropogenic material has led to popularisation of biased views.
{"title":"Evidence of the anthropogenic origin of the ‘Carmel sapphire’ with enigmatic super-reduced minerals","authors":"E. Galuskin, I. Galuskina","doi":"10.1180/mgm.2023.25","DOIUrl":"https://doi.org/10.1180/mgm.2023.25","url":null,"abstract":"Abstract Corundum with inclusions of enigmatic super-reduced minerals was found in mineral separates received as a result of alluvial sediment exploration near Mt Carmel, Israel by the Shefa Yamim Company. This corundum, registered as ‘Carmel sapphireTM’, has been an object of numerous publications by W. Griffin's scientific team, in which they propose a questionable hypothesis of sapphire formation at the crust–mantle boundary with the participation of CH4+H2 fluids. Typically the Carmel sapphire is in small fragments of breccia with white cement, which in the opinion of Griffin et al. is a carbonate-cemented volcanic ash. Our investigation of the ‘white breccia’ showed that it consists of unsorted angular fragments of Carmel sapphire from ~1 μm to 7 mm in size cemented by aluminium hydroxides (bauxite) and is a waste product of the fused alumina process, i.e. it has an anthropogenic origin. Phases typical for slags of fused alumina production and metallurgical slags were identified in the ‘white breccia’. Carmel sapphire has numerous microscopic spherical inclusions of Si–Fe alloy indicating that the removal of Si and Fe from the corundum melt occurred at a temperature >2000°С. Osbornite, TiN, from Carmel sapphire has a chemical zonation characteristic of osbornite from fused alumina with enrichment of central zones in carbon. Comparison of the growth heterogeneity of Carmel sapphire and ‘electrocorundum’ indicates that the crystallisation of the corundum melt proceeded in a similar way. Unfortunately, in the case of Carmel sapphire from the Carmel locality, the contamination of geological samples with anthropogenic material has led to popularisation of biased views.","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"87 1","pages":"619 - 630"},"PeriodicalIF":2.7,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44994394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yanjuan Wang, X. Gu, G. Dong, Z. Hou, F. Nestola, Zhusen Yang, Guang Fan, Yufei Wang, Kai Qu
Abstract Calcioancylite-(La), ideally (La,Ca)2(CO3)2(OH,H2O)2, has been discovered from nepheline syenite of the Gejiu alkaline complex in the Honghe Hani and Yi Autonomous Prefecture, Yunnan Province, China. The mineral occurs as aggregates of subhedral grains, and the size of single crystals varies between 5–20 μm. Calcioancylite-(La) is colourless to pale pinkish grey and has transparent to translucent lustre. It is brittle with a Mohs hardness of 4. The calculated density is 4.324 g/cm3. The mineral is biaxial (−), with α =1.662, β = 1.730, γ = 1.771, 2Vmeas. = 70°(1) and 2Vcalc. = 73°. Electron microprobe analysis for holotype material yielded an empirical formula of (La0.58Ce0.55Pr0.14Nd0.10Ca0.39Sr0.20K0.04)Σ2.00(CO3)2[(OH)1.25F0.06⋅0.69H2O]Σ2.00. Calcioancylite-(La) is orthorhombic, with space group Pmcn, a = 5.0253(3) Å, b = 8.5152(6) Å, c = 7.2717(6) Å, V = 311.17(4) Å3 and Z = 2. By using single-crystal X-ray diffraction, the crystal structure has been determined and refined to a final R1 = 0.0652 on the basis of 347 independent reflections (I > 2σ). The seven strongest powder X-ray diffraction lines [d in Å (I) (hkl)] are: 2.334 (100) (013), 2.970 (80) (121), 4.334 (75) (110), 3.678 (68) (111), 2.517 (55) (200), 2.647 (47) (031) and 2.077 (44) (221). Calcioancylite-(La) is the La-analogue of calcioancylite-(Ce) and is a new member of ancylite-group minerals. The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2021-090).
{"title":"Calcioancylite-(La), (La,Ca)2(CO3)2(OH,H2O)2, a new member of the ancylite group from Gejiu nepheline syenite, Yunnan Province, China","authors":"Yanjuan Wang, X. Gu, G. Dong, Z. Hou, F. Nestola, Zhusen Yang, Guang Fan, Yufei Wang, Kai Qu","doi":"10.1180/mgm.2023.28","DOIUrl":"https://doi.org/10.1180/mgm.2023.28","url":null,"abstract":"Abstract Calcioancylite-(La), ideally (La,Ca)2(CO3)2(OH,H2O)2, has been discovered from nepheline syenite of the Gejiu alkaline complex in the Honghe Hani and Yi Autonomous Prefecture, Yunnan Province, China. The mineral occurs as aggregates of subhedral grains, and the size of single crystals varies between 5–20 μm. Calcioancylite-(La) is colourless to pale pinkish grey and has transparent to translucent lustre. It is brittle with a Mohs hardness of 4. The calculated density is 4.324 g/cm3. The mineral is biaxial (−), with α =1.662, β = 1.730, γ = 1.771, 2Vmeas. = 70°(1) and 2Vcalc. = 73°. Electron microprobe analysis for holotype material yielded an empirical formula of (La0.58Ce0.55Pr0.14Nd0.10Ca0.39Sr0.20K0.04)Σ2.00(CO3)2[(OH)1.25F0.06⋅0.69H2O]Σ2.00. Calcioancylite-(La) is orthorhombic, with space group Pmcn, a = 5.0253(3) Å, b = 8.5152(6) Å, c = 7.2717(6) Å, V = 311.17(4) Å3 and Z = 2. By using single-crystal X-ray diffraction, the crystal structure has been determined and refined to a final R1 = 0.0652 on the basis of 347 independent reflections (I > 2σ). The seven strongest powder X-ray diffraction lines [d in Å (I) (hkl)] are: 2.334 (100) (013), 2.970 (80) (121), 4.334 (75) (110), 3.678 (68) (111), 2.517 (55) (200), 2.647 (47) (031) and 2.077 (44) (221). Calcioancylite-(La) is the La-analogue of calcioancylite-(Ce) and is a new member of ancylite-group minerals. The mineral and its name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA2021-090).","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"87 1","pages":"554 - 560"},"PeriodicalIF":2.7,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47464019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Chukanov, A. Sapozhnikov, E. Kaneva, D. Varlamov, M. Vigasina
Abstract Bystrite is redefined as a four-layer cancrinite-group mineral with the four-layer Losod-type framework and the end-member formula Na7Ca(Al6Si6O24)S52–Cl–. The mineral is known only at the Malo–Bystrinskoe gem lazurite deposit, Baikal Lake area, Siberia, Russia. The associated minerals are calcite, lazurite, sodalite, fluorapatite, phlogopite, diopside, dolomite and plagioclase. Bystrite is brittle, with the Mohs hardness of 5 and distinct cleavage on {10$bar{1}$0}. The yellow colour of bystrite is due to the presence of S52– anions occurring in Losod (LOS) cages of the aluminosilicate framework with the ABAC stacking sequence. Measured and calculated density is, respectively, 2.43(1) and 2.412 g cm–3 for the holotype and 2.42(1) and 2.428 g cm–3 for the cotype sample. Bystrite is uniaxial (+), ɛ = 1.660(2) and ω = 1.584(2). The mineral was characterised by infrared and Raman spectra. The empirical formulae of the holotype and cotype samples are Na6.97K0.04Ca0.98(Si6.03Al5.97O24)(S52–)0.93[(SO42–)0.15Cl0.83] and Na6.75K0.04Ca1.11(Si6.09Al5.91O24)(S52–)1.04[(HS–)0.17Cl0.85], respectively. Bystrite is trigonal, space group P31c. The unit-cell parameters are: a = 12.8527(6) Å, c = 10.6907(5) Å, V = 1529.4(1) Å3 and Z = 2. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 4.821 (32) (102), 3.915 (38) (211), 3.712 (100) (300), 3.307 (50) (212), 2.782 (18) (400), 2.692 (22) (401), 2.673 (30) (004) and 2.468 (23) (402). Isomorphism and genesis of bystrite-type minerals is discussed. Bystrite and its K,HS-analogue sulfhydrylbystrite, Na5K2Ca(Al6Si6O24)S52–(HS)–, are indicators of highly reducing conditions.
摘要Bystrite被重新定义为具有四层Losod型骨架的四层钙矾石族矿物，其端基分子式为Na7Ca（Al6Si6O24）S52–Cl–。该矿物仅在俄罗斯西伯利亚贝加尔湖地区的Malo–Bystrinskoe宝石-青金石矿床中已知。伴生矿物有方解石、天青石、方钠石、氟磷灰石、金云母、透辉石、白云石和斜长石。Bystrite是脆性的，莫氏硬度为5，在{10$bar{1}$0}上有明显的解理。bystrite的黄色是由于在具有ABAC堆叠序列的铝硅酸盐框架的Losod（LOS）笼中存在S52-阴离子。正模样品的测量密度和计算密度分别为2.43（1）和2.412 g cm–3，同型样品的测量和计算密度为2.42（1）或2.428 g cm–3。Bystrite为单轴（+），？=1.660（2），ω=1.584（2）。用红外光谱和拉曼光谱对其进行了表征。正模和共模样品的经验公式分别为Na6.97K0.04Ca0.98（Si6.03Al5.97O24）（S52-）0.93[（SO42-）0.15Cl0.83]和Na6.75K0.04Ca1.11（Si6.09Al5.91O24））（S52–）1.04[（HS–）0.17Cl0.85]。Bystrite是三角的，空间群P31c。晶胞参数为：a=12.8527（6）Å，c=10.6907（5）Å、V=1529.4（1）Å3和Z=2。粉末X射线衍射图的最强谱线[d，Å（I，%）（hkl）]为：4.821（32）（102）、3.915（38）（211）、3.712（100）（300）、3.307（50）（212）、2.782（18）（400）、2.692（22）（401）、2.673（30）（004）和2.468（23）（402）。讨论了榴石型矿物的同构性和成因。亚镁石及其K，HS类似物巯基亚镁石Na5K2Ca（Al6Si6O24）S52–（HS）–是高度还原条件的指标。
{"title":"Bystrite, Na7Ca(Al6Si6O24)S52–Cl–: formula redefinition and relationships with other four-layer cancrinite-group minerals","authors":"N. Chukanov, A. Sapozhnikov, E. Kaneva, D. Varlamov, M. Vigasina","doi":"10.1180/mgm.2023.29","DOIUrl":"https://doi.org/10.1180/mgm.2023.29","url":null,"abstract":"Abstract Bystrite is redefined as a four-layer cancrinite-group mineral with the four-layer Losod-type framework and the end-member formula Na7Ca(Al6Si6O24)S52–Cl–. The mineral is known only at the Malo–Bystrinskoe gem lazurite deposit, Baikal Lake area, Siberia, Russia. The associated minerals are calcite, lazurite, sodalite, fluorapatite, phlogopite, diopside, dolomite and plagioclase. Bystrite is brittle, with the Mohs hardness of 5 and distinct cleavage on {10$bar{1}$0}. The yellow colour of bystrite is due to the presence of S52– anions occurring in Losod (LOS) cages of the aluminosilicate framework with the ABAC stacking sequence. Measured and calculated density is, respectively, 2.43(1) and 2.412 g cm–3 for the holotype and 2.42(1) and 2.428 g cm–3 for the cotype sample. Bystrite is uniaxial (+), ɛ = 1.660(2) and ω = 1.584(2). The mineral was characterised by infrared and Raman spectra. The empirical formulae of the holotype and cotype samples are Na6.97K0.04Ca0.98(Si6.03Al5.97O24)(S52–)0.93[(SO42–)0.15Cl0.83] and Na6.75K0.04Ca1.11(Si6.09Al5.91O24)(S52–)1.04[(HS–)0.17Cl0.85], respectively. Bystrite is trigonal, space group P31c. The unit-cell parameters are: a = 12.8527(6) Å, c = 10.6907(5) Å, V = 1529.4(1) Å3 and Z = 2. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 4.821 (32) (102), 3.915 (38) (211), 3.712 (100) (300), 3.307 (50) (212), 2.782 (18) (400), 2.692 (22) (401), 2.673 (30) (004) and 2.468 (23) (402). Isomorphism and genesis of bystrite-type minerals is discussed. Bystrite and its K,HS-analogue sulfhydrylbystrite, Na5K2Ca(Al6Si6O24)S52–(HS)–, are indicators of highly reducing conditions.","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"87 1","pages":"455 - 464"},"PeriodicalIF":2.7,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43057054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Hatert, S. Mills, M. Pasero, R. Miyawaki, F. Bosi
Abstract New guidelines for the nomenclature of polymorphs and polysomes have been approved by the the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA–CNMNC). Several cases can be distinguished. (i) Polymorphs with different crystal systems are distinguished by the prefixes cubo- (cubic), hexa- (hexagonal), tetra- (tetragonal), trigo- (trigonal), ortho- (orthorhombic), clino- (monoclinic) and anortho- (triclinic). (ii) Polymorphs with different crystal systems but showing a pseudosymmetry should show the prefix ‘pseudo-’. (iii) Polymorphs with the same crystal system but different space groups are distinguished by the prefix ‘para-’. If three or more polymorphs show the same crystal system but different space groups, the space group notation may be added as a suffix, though such a nomenclature should be avoided if possible. (iv) Polymorphs with the same space group are distinguished by the prefix ‘para-’. (v) Minerals with polymorph suffixes but with different chemical compositions cannot be considered as true polymorphs, so we recommend using the prefix ‘meta-’, which indicates a close but significantly different chemical composition. (vi) Polysomatic symbols should be placed as a suffix, which indicates the number and types of modules that alternate in the structure, such as in the högbomite supergroup, or as prefixes as in the sartorite homologous series. These recommendations have to be applied for future new mineral proposals, when the authors decide to use structural prefixes or suffixes, however modifications of historical and well-established names have to pass through the CNMNC for approval. In order to be consistent with the new guidelines, 25 mineral names are now modified: domeykite-β becomes trigodomeykite; fergusonite-(Y)-β becomes clinofergusonite-(Y); fergusonite-(Ce)-β becomes clinofergusonite-(Ce); fergusonite-(Nd)-β becomes clinofergusonite-(Nd); ice-VII becomes cubo-ice; roselite-β becomes anorthoroselite; sulphur-β becomes clinosulphur; mertieite-II becomes mertieite; mertieite-I becomes pseudomertieite; uranophane-α becomes uranophane; uranophane-β becomes parauranophane; gersdorffite-P213 becomes gersdorffite; gersdorffite-Pa3 becomes paragersdorffite; gersdorffite-Pca21 becomes orthogersdorffite; betalomonosovite becomes paralomonosovite; lammerite-β becomes paralammerite; nováčekite-I becomes hydronováčekite; nováčekite-II becomes nováčekite; halloysite-7Å becomes halloysite; halloysite-10Å becomes hydrohalloysite; metauranocircite-I becomes metauranocircite; taimyrite-I becomes taimyrite; uranocircite-II becomes uranocircite; andorite IV becomes quatrandorite; and andorite VI becomes senandorite.
{"title":"CNMNC guidelines for the nomenclature of polymorphs and polysomes","authors":"F. Hatert, S. Mills, M. Pasero, R. Miyawaki, F. Bosi","doi":"10.1180/mgm.2023.13","DOIUrl":"https://doi.org/10.1180/mgm.2023.13","url":null,"abstract":"Abstract New guidelines for the nomenclature of polymorphs and polysomes have been approved by the the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA–CNMNC). Several cases can be distinguished. (i) Polymorphs with different crystal systems are distinguished by the prefixes cubo- (cubic), hexa- (hexagonal), tetra- (tetragonal), trigo- (trigonal), ortho- (orthorhombic), clino- (monoclinic) and anortho- (triclinic). (ii) Polymorphs with different crystal systems but showing a pseudosymmetry should show the prefix ‘pseudo-’. (iii) Polymorphs with the same crystal system but different space groups are distinguished by the prefix ‘para-’. If three or more polymorphs show the same crystal system but different space groups, the space group notation may be added as a suffix, though such a nomenclature should be avoided if possible. (iv) Polymorphs with the same space group are distinguished by the prefix ‘para-’. (v) Minerals with polymorph suffixes but with different chemical compositions cannot be considered as true polymorphs, so we recommend using the prefix ‘meta-’, which indicates a close but significantly different chemical composition. (vi) Polysomatic symbols should be placed as a suffix, which indicates the number and types of modules that alternate in the structure, such as in the högbomite supergroup, or as prefixes as in the sartorite homologous series. These recommendations have to be applied for future new mineral proposals, when the authors decide to use structural prefixes or suffixes, however modifications of historical and well-established names have to pass through the CNMNC for approval. In order to be consistent with the new guidelines, 25 mineral names are now modified: domeykite-β becomes trigodomeykite; fergusonite-(Y)-β becomes clinofergusonite-(Y); fergusonite-(Ce)-β becomes clinofergusonite-(Ce); fergusonite-(Nd)-β becomes clinofergusonite-(Nd); ice-VII becomes cubo-ice; roselite-β becomes anorthoroselite; sulphur-β becomes clinosulphur; mertieite-II becomes mertieite; mertieite-I becomes pseudomertieite; uranophane-α becomes uranophane; uranophane-β becomes parauranophane; gersdorffite-P213 becomes gersdorffite; gersdorffite-Pa3 becomes paragersdorffite; gersdorffite-Pca21 becomes orthogersdorffite; betalomonosovite becomes paralomonosovite; lammerite-β becomes paralammerite; nováčekite-I becomes hydronováčekite; nováčekite-II becomes nováčekite; halloysite-7Å becomes halloysite; halloysite-10Å becomes hydrohalloysite; metauranocircite-I becomes metauranocircite; taimyrite-I becomes taimyrite; uranocircite-II becomes uranocircite; andorite IV becomes quatrandorite; and andorite VI becomes senandorite.","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"87 1","pages":"225 - 232"},"PeriodicalIF":2.7,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41819884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
O. Rybnikova, P. Uher, M. Novak, Š. Chládek, P. Bačík, S. Kurylo, T. Vaculovič
Abstract The Maršíkov–Schinderhübel III pegmatite in the Hrubý Jeseník Mountains, Silesian Domain, Czech Republic, is a classic example of chrysoberyl-bearing LCT granitic pegmatite of beryl–columbite subtype. This thin pegmatite dyke, (up to 1 m in thickness in biotite–amphibole gneiss is characterised by symmetrical internal zoning. Tabular and prismatic chrysoberyl crystals (≤3 cm) occur typically in the intermediate albite-rich unit and rarely in the quartz core. Chrysoberyl microtextures are quite complex; their crystals are irregularly patchy, concentric or fine oscillatory zoned with large variations in Fe content (1.1–5.3 wt.% Fe2O3; ≤0.09 apfu). Chrysoberyl compositions reveal dominant Fe3+ = Al3+ and minor Fe2+ + Ti4+ = 2(Al, Fe)3+ substitution mechanisms in the octahedral sites. Tin, Ga, and V (determined by LA-ICP-MS) are characteristic trace elements incorporated in the chrysoberyl structure, whereas anomalously high Ta and Nb concentrations (thousands ppm) in chrysoberyl are probably caused by nano- to micro-inclusions of Nb–Ta oxide minerals; especially columbite–tantalite. Textural relationships between associated minerals, distinct schistosity of the pegmatite parallel to the host gneiss foliation and fragmentation of the pegmatite body into blocks as a result of superimposed stress are clear evidence for deformation and metamorphic overprinting of the pegmatite. Primary magmatic beryl, albite and muscovite were transformed to chrysoberyl, fibrolitic sillimanite, secondary quartz and muscovite during a high-temperature (~600°C) and medium-pressure (~250–500 MPa) prograde metamorphic stage under amphibolite-facies conditions. A subsequent retrograde, low-temperature (~200–500°C) and pressure (≤250 MPa) metamorphic stage resulted in the local alteration of chrysoberyl to secondary Fe,Na-rich beryl, euclase, bertrandite and late muscovite.
{"title":"Chrysoberyl and associated beryllium minerals resulting from metamorphic overprinting of the Maršíkov–Schinderhübel III pegmatite, Czech Republic","authors":"O. Rybnikova, P. Uher, M. Novak, Š. Chládek, P. Bačík, S. Kurylo, T. Vaculovič","doi":"10.1180/mgm.2023.22","DOIUrl":"https://doi.org/10.1180/mgm.2023.22","url":null,"abstract":"Abstract The Maršíkov–Schinderhübel III pegmatite in the Hrubý Jeseník Mountains, Silesian Domain, Czech Republic, is a classic example of chrysoberyl-bearing LCT granitic pegmatite of beryl–columbite subtype. This thin pegmatite dyke, (up to 1 m in thickness in biotite–amphibole gneiss is characterised by symmetrical internal zoning. Tabular and prismatic chrysoberyl crystals (≤3 cm) occur typically in the intermediate albite-rich unit and rarely in the quartz core. Chrysoberyl microtextures are quite complex; their crystals are irregularly patchy, concentric or fine oscillatory zoned with large variations in Fe content (1.1–5.3 wt.% Fe2O3; ≤0.09 apfu). Chrysoberyl compositions reveal dominant Fe3+ = Al3+ and minor Fe2+ + Ti4+ = 2(Al, Fe)3+ substitution mechanisms in the octahedral sites. Tin, Ga, and V (determined by LA-ICP-MS) are characteristic trace elements incorporated in the chrysoberyl structure, whereas anomalously high Ta and Nb concentrations (thousands ppm) in chrysoberyl are probably caused by nano- to micro-inclusions of Nb–Ta oxide minerals; especially columbite–tantalite. Textural relationships between associated minerals, distinct schistosity of the pegmatite parallel to the host gneiss foliation and fragmentation of the pegmatite body into blocks as a result of superimposed stress are clear evidence for deformation and metamorphic overprinting of the pegmatite. Primary magmatic beryl, albite and muscovite were transformed to chrysoberyl, fibrolitic sillimanite, secondary quartz and muscovite during a high-temperature (~600°C) and medium-pressure (~250–500 MPa) prograde metamorphic stage under amphibolite-facies conditions. A subsequent retrograde, low-temperature (~200–500°C) and pressure (≤250 MPa) metamorphic stage resulted in the local alteration of chrysoberyl to secondary Fe,Na-rich beryl, euclase, bertrandite and late muscovite.","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"87 1","pages":"369 - 381"},"PeriodicalIF":2.7,"publicationDate":"2023-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43737770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
O. Vereshchagin, L. Gorelova, Anastasia K. Shagova, A. Kasatkin, R. Škoda, V. Bocharov, N. S. Vlasenko, M. Vašinová Galiová
Abstract The chemical composition (including B, Be and Li), the Raman spectrum and the crystal-structure evolution (at the temperature range 27–1000°C) of a Mn-bearing, Bi-rich gadolinite-subgroup mineral from the Jaguaraçu Pegmatite, Brazil (type-locality of minasgeraisite-(Y)) was studied. Elemental mapping revealed that the crystal investigated has complex chemical zonation with various Bi (~8–24 wt.% Bi2O3), Ca (~8–10 wt.% CaO) and Y (~11–17 wt.% Y2O3) content. The sample investigated has all the specific features of the chemical composition of minasgeraisite-(Y), except Ca excess and, thus, should be considered as hingganite-(Y). The Raman spectrum of the sample under study has bands at 140, 179, 243, 350, 446, 519, 559, 625, 902, 973, 3224, 3353, 3532 and 3763 cm–1, and is similar to that of hingganite-(Y) / -(Nd). Crystal-structure refinement confirmed that the crystal in question should be considered as hingganite-(Y) and is in line with the previously obtained data on gadolinite-subgroup minerals from the Jaguaraçu Pegmatite. High-temperature single-crystal X-ray diffraction studies revealed that the mineral starts to decompose above 800°C. We can conclude that beryllosilicates are most stable at high-temperature conditions within the gadolinite supergroup and that species with a higher M-site occupancy have higher stability upon heating.
{"title":"Re-investigation of ‘minasgeraisite-(Y)’ from the Jaguaraçu pegmatite, Brazil and high-temperature crystal chemistry of gadolinite-supergroup minerals","authors":"O. Vereshchagin, L. Gorelova, Anastasia K. Shagova, A. Kasatkin, R. Škoda, V. Bocharov, N. S. Vlasenko, M. Vašinová Galiová","doi":"10.1180/mgm.2023.19","DOIUrl":"https://doi.org/10.1180/mgm.2023.19","url":null,"abstract":"Abstract The chemical composition (including B, Be and Li), the Raman spectrum and the crystal-structure evolution (at the temperature range 27–1000°C) of a Mn-bearing, Bi-rich gadolinite-subgroup mineral from the Jaguaraçu Pegmatite, Brazil (type-locality of minasgeraisite-(Y)) was studied. Elemental mapping revealed that the crystal investigated has complex chemical zonation with various Bi (~8–24 wt.% Bi2O3), Ca (~8–10 wt.% CaO) and Y (~11–17 wt.% Y2O3) content. The sample investigated has all the specific features of the chemical composition of minasgeraisite-(Y), except Ca excess and, thus, should be considered as hingganite-(Y). The Raman spectrum of the sample under study has bands at 140, 179, 243, 350, 446, 519, 559, 625, 902, 973, 3224, 3353, 3532 and 3763 cm–1, and is similar to that of hingganite-(Y) / -(Nd). Crystal-structure refinement confirmed that the crystal in question should be considered as hingganite-(Y) and is in line with the previously obtained data on gadolinite-subgroup minerals from the Jaguaraçu Pegmatite. High-temperature single-crystal X-ray diffraction studies revealed that the mineral starts to decompose above 800°C. We can conclude that beryllosilicates are most stable at high-temperature conditions within the gadolinite supergroup and that species with a higher M-site occupancy have higher stability upon heating.","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"87 1","pages":"470 - 479"},"PeriodicalIF":2.7,"publicationDate":"2023-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44867922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Novak, Z. Dolníček, A. Zachař, P. Gadas, Miroslav Nepejchal, Kamil Sobek, R. Škoda, L. Vrtiška
Abstract The paragenesis and composition of bavenite–bohseite were investigated in fifteen granitic pegmatites from the Bohemian Massif, Czech Republic. Three types distinct in their relation to primary Be precursors, mineral assemblages, morphology and origin were recognised: (1) primary hydrothermal bavenite–bohseite crystallised in miarolitic pockets from residual pegmatite fluids; and secondary bavenite–bohseite in two distinct types: (2) a proximal type restricted spatially to pseudomorphs after a primary Be mineral (beryl > phenakite, helvine–danalite); and (3) a distal type on brittle fractures and fissures of host pegmatite. The mineral assemblages are highly variable: (1) axinite-(Mn), smectite, calcite and pyrite; (2) bertrandite, milarite, secondary beryl, bazzite, K-feldspar, muscovite–illite, scolecite, gismondine-Ca, analcime, chlorite; and (3) muscovite, albite, quartz, epidote, pumpellyite-(Mg), pumpellyite-(Fe3+), titanite and chlorite. Electron microprobe analyses showed, in addition to major constituents (Si, Ca and Al), minor concentrations (in apfu) of Na (≤0.24), Fe (≤0.10), Mn (≤0.10) and F (≤0.36). The type 1 hydrothermal miarolitic bavenite–bohseite is mostly Al-rich (2.00–0.67 apfu) relative to type 2 proximal bavenite–bohseite and bohseite after beryl, phenakite and helvine–danalite (1.56–0.46, 0.70–0.05, 1.02–0.35 apfu, respectively); and type 3 distal bavenite–bohseite typically after beryl (1.63–0.09 apfu). Raman spectroscopy revealed that the distance between the OH– vibrational modes decreases with increasing bohseite component. The Al content of secondary type 2 proximal bavenite–bohseite is controlled by the composition of the Be precursor whereas type 3 distal bavenite–bohseite with beryl as the Be precursor is more variable and the composition is governed mainly by the composition of fluids. Calcium, a crucial component for bavenite–bohseite origins, was derived from residual pegmatite fluids (Vlastějovice, Vepice IV or Třebíč Plutons) or external sources (e.g. Drahonín IV, Věžná I or Maršíkov). Primary type 1 hydrothermal bavenite–bohseite from miarolitic pockets might have crystallised at T ≈ 300–400°C and P ≈ 200 MPa, whereas the secondary type 2 and 3 bavenite–bohseite formed at T ≈ 300–100°C and P ≈ 200–20 MPa.
{"title":"Mineral assemblages and compositional variations in bavenite–bohseite from granitic pegmatites of the Bohemian Massif, Czech Republic","authors":"M. Novak, Z. Dolníček, A. Zachař, P. Gadas, Miroslav Nepejchal, Kamil Sobek, R. Škoda, L. Vrtiška","doi":"10.1180/mgm.2023.17","DOIUrl":"https://doi.org/10.1180/mgm.2023.17","url":null,"abstract":"Abstract The paragenesis and composition of bavenite–bohseite were investigated in fifteen granitic pegmatites from the Bohemian Massif, Czech Republic. Three types distinct in their relation to primary Be precursors, mineral assemblages, morphology and origin were recognised: (1) primary hydrothermal bavenite–bohseite crystallised in miarolitic pockets from residual pegmatite fluids; and secondary bavenite–bohseite in two distinct types: (2) a proximal type restricted spatially to pseudomorphs after a primary Be mineral (beryl > phenakite, helvine–danalite); and (3) a distal type on brittle fractures and fissures of host pegmatite. The mineral assemblages are highly variable: (1) axinite-(Mn), smectite, calcite and pyrite; (2) bertrandite, milarite, secondary beryl, bazzite, K-feldspar, muscovite–illite, scolecite, gismondine-Ca, analcime, chlorite; and (3) muscovite, albite, quartz, epidote, pumpellyite-(Mg), pumpellyite-(Fe3+), titanite and chlorite. Electron microprobe analyses showed, in addition to major constituents (Si, Ca and Al), minor concentrations (in apfu) of Na (≤0.24), Fe (≤0.10), Mn (≤0.10) and F (≤0.36). The type 1 hydrothermal miarolitic bavenite–bohseite is mostly Al-rich (2.00–0.67 apfu) relative to type 2 proximal bavenite–bohseite and bohseite after beryl, phenakite and helvine–danalite (1.56–0.46, 0.70–0.05, 1.02–0.35 apfu, respectively); and type 3 distal bavenite–bohseite typically after beryl (1.63–0.09 apfu). Raman spectroscopy revealed that the distance between the OH– vibrational modes decreases with increasing bohseite component. The Al content of secondary type 2 proximal bavenite–bohseite is controlled by the composition of the Be precursor whereas type 3 distal bavenite–bohseite with beryl as the Be precursor is more variable and the composition is governed mainly by the composition of fluids. Calcium, a crucial component for bavenite–bohseite origins, was derived from residual pegmatite fluids (Vlastějovice, Vepice IV or Třebíč Plutons) or external sources (e.g. Drahonín IV, Věžná I or Maršíkov). Primary type 1 hydrothermal bavenite–bohseite from miarolitic pockets might have crystallised at T ≈ 300–400°C and P ≈ 200 MPa, whereas the secondary type 2 and 3 bavenite–bohseite formed at T ≈ 300–100°C and P ≈ 200–20 MPa.","PeriodicalId":18618,"journal":{"name":"Mineralogical Magazine","volume":"87 1","pages":"415 - 432"},"PeriodicalIF":2.7,"publicationDate":"2023-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41883637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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