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| 3. |
- Cámara, Fernando, 1967-, et al.
(författare)
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Old samples - new amphiboles
- 2022
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Ingår i: Abstracts, International Mineralogical Association 23<sup>rd</sup> General meeting. - Lyon. ; , s. 42-42
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The scientific value of old and well-preserved collections is priceless. Samples that already have been studied and described can still give very useful information. For instance, minerals with complex solid solutions like amphiboles sometimes show new compositions that are feasible because of crystal-chemistry and charge arrangements, based on the current classification scheme by Hawthorne et al. (2012) for the amphibole supergroup. In the last four years, a fruitful collaboration between the Swedish Museum of Natural History and the Department of Earth Sciences of the University of Milan has allowed the identification of new amphibole species, recognized by CNMNC-IMA. First of all, we identified hjalmarite, [ANaB(NaMn)CMg5TSi8O22W(OH)2], which is related to richterite via the homovalent substitution [B]Ca2+ → [B]Mn2+, and is the second recognized member of the sodium–(magnesium–iron–manganese) subgroup, after ferri-ghoseite. Sjögren (1891) had described a physically similar, MnO-rich sample from Långban, named “astochit”. A related amphibole, although belonging to a different subgroup, that we have formally described is potassic-richterite, [AKB(NaCa)CMg5TSi8O22W(OH)2]. It was found in a sample from the Pajsberg iron and manganese ore mines, which was originally collected by the mineralogist Lars Johan Igelström, probably in the 1850s. The most recent amphibole we have described is ferri-taramite [ANaB(NaCa)C(Mg3Fe3+2)T(Si6Al2)O22W(OH)2], found in a skarn sample from the Jakobsberg manganese mine: it was once examined by Flink (1914), who noted the unusual character of the amphibole and described it as a “strange hornblende”.
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- Cámara, Fernando, 1967-, et al.
(författare)
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Zinkgruvanite, Ba4Mn2+4Fe3+2(Si2O7)2(SO4)2O2(OH)2, a new ericssonite-group mineral from the Zinkgruvan Zn-Pb-Ag-Cu deposit, Askersund, Örebro County, Sweden.
- 2021
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Ingår i: European journal of mineralogy. - : Nicolaus Copernicus University Press. - 0935-1221 .- 1617-4011. ; 33:6, s. 659-673
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Tidskriftsartikel (refereegranskat)abstract
- Zinkgruvanite, ideally Ba4Mn2+4Fe3+2(Si2O7)2(SO4)2O2(OH)2, is a new member of the ericssonite group, found in Ba-rich drill core samples from a sphalerite+galena- and diopside-rich metatuffite succession from the Zinkgruvan mine, Örebro county, Sweden. Zinkgruvanite is associated with massive baryte, barytocalcite, diopside and minor witherite, cerchiaraite-(Al) and sulfide minerals. It occurs as subhedral to euhedral flattened and elongated crystals up to 4 mm. It is almost black, semi-opaque with a dark brown streak. The luster is vitreous to sub-adamantine on crystal faces, resinous on fractures. The mineral is brittle with an uneven fracture. VHN100 = 539 and HMohs ~4½. In thin fragments, it is reddish-black, translucent and optically biaxial (+), 2Vz > 70°. Pleochroism is strong, deep brown-red (E ⊥ {001} cleavage) to olive-pale brown. Chemical point analyses by WDS-EPMA together with iron valencies determined from Mössbauer spectroscopy, yielded the empirical formula (based on 26 O+OH+F+Cl anions): (Ba4.02Na0.03)Σ4.05(Mn1.79Fe2+1.56Fe3+0.42Mg0.14Ca0.10Ni0.01Zn0.01)Σ4.03 (Fe3+1.74Ti0.20Al0.06)Σ2.00Si4(S1.61Si0.32P0.07)Σ1.99O24(OH1.63Cl0.29F0.08)Σ2.00. The mineral is triclinic, space group P–1, with unit-cell parameters a = 5.3982(1) Å, b = 7.0237(1) Å, c = 14.8108(4) Å, α = 98.256(2)º, β = 93.379(2)º, γ = 89.985(2)º and V = 554.75(2) Å3 for Z = 1. The eight strongest X-ray powder diffraction lines are [d Å (I%; hkl)]: 3.508 (70; 103), 2.980(70; 11–4), 2.814 (68; 1–22), 2.777 (70; 121), 2.699 (714; 200), 2.680 (68; 20–1), 2.125 (100; 124, 204), 2.107 (96; –221). The crystal structure (R1 = 0.0379 for 3204 reflections) is an array of TS (titanium silicate) blocks alternating with intermediate blocks. The TS blocks consist of HOH sheets (H = heteropolyhedral, O = octahedral) parallel to (001). In the O sheet, the Mn2+-dominant MO(1,2,3) sites give ideally Mn2+4 pfu. In the H sheet, the Fe3+-dominant MH sites and AP(1) sites give ideally Fe3+2Ba2 pfu. In the intermediate block, SO4 oxyanions and eleven coordinated Ba atoms give ideally 2 × SO4Ba pfu. Zinkgruvanite is related to ericssonite and ferro-ericssonite in having the same topology and type of linkage of layers in the TS block. Zinkgruvanite is also closely compositionally related to yoshimuraite, Ba4Mn4Ti2(Si2O7)2(PO4)2O2(OH)2, via the coupled heterovalent substitution 2 Ti4+ + 2 (PO4)3- →2 Fe3+ + 2 (SO4)2-, but presents a different type of linkage. The new mineral probably formed during a late stage of regional metamorphism of a Ba-enriched, syngenetic protolith, involving locally generated oxidized fluids of high salinity.
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- Holtstam, Dan, 1963-, et al.
(författare)
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An 18th century find of an erratic lazulite-andalusite-quartz boulder in Södermanland, Sweden, and its implications
- 2019
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Ingår i: GFF. - Stockholm : Taylor & Francis. - 1103-5897 .- 2000-0863. ; 141:3, s. 216-221
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Tidskriftsartikel (refereegranskat)abstract
- At some point in the 1750s, a jeweller-apprentice by the name Jacob Hässelgren found an erratic bouldernext to the Eskilstuna country road in the neighbourhood of Ärla in Södermanland. It contained a deep bluemass of lazulite, at the time an unknown mineral. Pieces of the find eventually reached Daniel Tilas, TorbernBergman and Axel Fredrik Cronstedt ˗ renowned natural scientists in Sweden ˗ but no detailed studies of thematerial seem to have been carried out by them. Two fragments of the original boulder are still preserved,and a recent examination shows them to consist of mainly lazulite, andalusite, quartz, pyrophyllite, augeliteand svanbergite. The average composition of lazulite is Mg0.700Fe2+0.261Mn0.003Al1.954Fe3+0.017 P2.031O8(OH)2.The mineral assemblage is characteristic of known occurrences of phosphate-Al silicate-quartz appearingalong the Protogine Zone in southern Sweden. Transportation of the boulder from its source rock, likely tobe located somewhere along the Protogine Zone, ought to have occurred in connection with the developmentof the Fennoscandian ice sheet during the final Weichselian deglaciation, and the material waspossibly discharged from floating ice on the Yoldia Sea.
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- Holtstam, Dan, 1963-, et al.
(författare)
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An unusual mineral assemblage of Pb silicates
- 2022
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Ingår i: Geological Society of Sweden, 150 year anniversary meeting, Uppsala, August 17–19 2022, Abstract volume.. - Uppsala. - 9789198783308 ; , s. 356-357
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Konferensbidrag (refereegranskat)abstract
- Rare assemblages of Pb silicates, from skarn in the Långban and Pajsbergs mines, Värmland, Sweden, have been investigated. Minerals observed are alamosite, barysilite, jagoite, joesmithite, melanotekite, nasonite and yangite, together with common metamorphic skarn components like andradite, diopside, hematite and quartz. Jagoite likely formed from primary melanotekite and quartz under the influence of a fluid with high Cl activity. Jagoite is prone to hydrothermal alteration, producing unidentified phases in the system CaO–PbO–SiO2–H2O–(±Cl2).
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| 7. |
- Holtstam, Dan, 1963-, et al.
(författare)
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Arrheniusite-(Ce), CaMg[(Ce7Y3)Ca5](SiO4)3(Si3B3O18)(AsO4)(BO3)F11, a new member of the vicanite group, from the Östanmossa mine, Norberg, Sweden
- 2021
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Ingår i: Canadian Mineralogist. - : Geological and Mineralogical Association of Canada. - 0008-4476 .- 1499-1276. ; 59, s. 177-189
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Tidskriftsartikel (refereegranskat)abstract
- Arrheniusite-(Ce) is a new mineral (IMA 2019-086) from the Östanmossa mine, one of the Bastnäs-type deposits in the Bergslagen ore region, Sweden. It occurs in a metasomatic F-rich skarn, associated with dolomite, tremolite, talc, magnetite, calcite, pyrite, dollaseite-(Ce), parisite-(Ce), bastnäsite-(Ce), fluorbritholite-(Ce) and gadolinite-(Nd). Arrheniusite-(Ce) forms anhedral, greenish-yellow translucent grains, up to 0.8 mm exceptionally. It is optically uniaxial (-), with ω = 1.750(5), ε = 1.725(5), and non-pleochroic in thin section. The calculated density is 4.78(1) g/cm3. Arrheniusite-(Ce) is trigonal, space group R3m, with unit-cell parameters a = 10.8082(3) Å, c = 27.5196(9) Å, and V = 2784.07(14) Å3 for Z = 3. The crystal structure was refined from X-ray diffraction data to R1 = 3.85 for 2286 observed reflections [Fo > 4σ(Fo)]. The empirical formula for the fragment used for the structural study, based on EPMA data and results from the structure refinement, is (Ca0.65As3+0.35)Σ1(Mg0.57Fe2+0.30As5+0.10Al0.03)Σ1[(Ce2.24Nd2.13La0.86Gd0.74Sm0.71Pr0.37)Σ7.05(Y2.76Dy0.26Er0.11Tb0.08Tm0.01Ho0.04Yb0.01)Σ3.27Ca4.14]Σ14.46(SiO4)3[(Si3.26B2.74)Σ6O17.31F0.69][(As5+0.65Si0.22P0.13)Σ1O4](B0.77O3)F11; the ideal formula obtained is CaMg[(Ce7Y3)Ca5](SiO4)3(Si3B3O18)(AsO4)(BO3)F11. Arrheniusite-(Ce) belongs to the vicanite group of minerals, and is distinct from other isostructural members mainly by having a Mg-dominant, octahedrally coordinated site (M6); it can be considered as a Mg-As analog to hundholmenite-(Y). The three-fold coordinated T5 site is partly occupied by B, like in laptevite-(Ce) and vicanite-(Ce). The mineral name honors C.A. Arrhenius (1757–1824), a Swedish officer and chemist, who first discovered gadolinite-(Y), from the famous Ytterby pegmatite quarry.
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| 8. |
- Holtstam, Dan, 1963-
(författare)
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Cronstedt 300 år
- 2022
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Ingår i: Geologiskt forum. - : Geologiska Föreningen. - 1104-4721. ; 114, s. 12-16
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Axel Fredrik Cronstedt (1722-1765) är en av de mest kända svenskarna inom mineralogin. Han beskrev nya grundämnen och mineral samt presenterade ett nydanande klassificeringssystem. Detta byggde på mineralens kemiska sammansättning snarare än deras yttre egenskaper.
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| 9. |
- Holtstam, Dan, 1963-, et al.
(författare)
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Crystal structure and composition of hiärneite, Ca2Zr4Mn3+SbTiO16, and constitution of the calzirtite group
- 2022
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Ingår i: Mineralogical magazine. - : Mineralogical Society. - 0026-461X .- 1471-8022. ; 86:2, s. 314-318
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Tidskriftsartikel (refereegranskat)abstract
- The crystal structure of hiärneite has been refined from single-crystal X-ray diffraction data (λ = 0.71073 Å) on type material from Långban, Värmland, Sweden. The refinement converged to R1 = 0.046 based on 1073 reflections with F2 > 4σ(F2). The tetragonal unit cell, space group I41/acd, has the parameters a = 15.2344(6) Å and c = 10.0891(6) Å with Z = 8. The mineral is isostructural with calzirtite, ideally Ca2Zr5Ti2O16, with a structural topology derived from fluorite. In hiärneite, Mn3+ is ordered at a 4- to 8-fold coordinated site (with a distorted polyhedral coordination figure), without the atom splitting encountered at the corresponding Zr-dominated site of calzirtite. The end-member formula for hiärneite is established as Ca2Zr4Mn3+SbTiO16. The calzirtite group, with calzirtite, hiärneite and tazheranite (cubic ZrO2-x), has been approved by the IMA–CNMNC.
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| 10. |
- Holtstam, Dan, 1963-
(författare)
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Den outsläckliga törsten efter kobolt
- 2019
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Ingår i: Geologiskt forum. - Stockholm. - 1104-4721. ; 2019:103, s. 25-28
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- The shift to electric vehicles and the growing production of rechargeable batteries needed in these have dramatically increased the global demand for cobalt. Most of the metal comes from less stable areas in the world, which makes the supply precarious. The article describes the present situation (in Swedish), and gives a brief overview of the main sources of cobalt in the world today and the prospects for exploiting reserves in Sweden.
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