Late hydrothermal events at LÅngban – how many and how alkaline?

Boström, Kürt

doi:10.1080/11035890201244236

Cited by 2 publications

(2 citation statements)

References 13 publications

(15 reference statements)

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“…Micro-thermometric data from fluid inclusions of minerals in late-fissure Pb-As-Sb-Mn assemblages at the deposit indicate formation temperatures below 180 °C and a close to near-surface, low-pressure regime (Jonsson and Broman, 2002). The conditions of formation here were reduced enough to stabilize Sb 3+ and Fe 2+ in the present new minerals but probably less so than in the more persistent native lead-pyrochroite veins characteristic of the Långban D period (Boström, 2002) and in other late-formed mineral assemblages containing native elements (As, Sb). It is notable that in earlier-formed skarn matrices, Sb has only been observed in the pentavalent form in the Långban-type deposits (Holtstam et al, 1998).…”

Section: Paragenesismentioning

confidence: 72%

Igelströmite, Fe³⁺(Sb³⁺Pb²⁺)O₄, and manganoschafarzikite, Mn²⁺Sb³⁺₂O₄, two new members of the newly established minium group, from the Långban Mn–Fe deposit, Värmland, Sweden

Holtstam,

Langhof,

Friis

et al. 2024

Eur. J. Mineral.

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Abstract. The two new minerals igelströmite, Fe3+(Sb3+Pb2+)O4, and manganoschafarzikite, Mn2+Sb23+O4, are found in the Långban Fe–Mn deposit, in open fractures in a fine-grained hematite ore, with minor amounts of aegirine, a serpentine-group mineral, fluorcalcioroméite, baryte, nadorite, mimetite and other late-stage minerals. Igelströmite is named after the Swedish geologist–mineralogist Lars Johan Igelström (1822–1897). Mohs hardness = 3–4 and Dcalc= 6.33(1) and 5.37(2) g cm−3 for igelströmite and manganoschafarzikite, respectively. Cleavage is distinct on {110}. Both minerals are brittle, with an uneven to conchoidal fracture. The chemical formulae obtained from microprobe data are (Fe0.593+Mn0.292+As0.063+Fe0.062+)Σ=1.00(Sb1.243+Pb0.652+As0.113+)Σ=2.00O4 and (Mn0.642+Fe0.252+Mg0.08)Σ=0.97(Sb1.973+As0.033+Pb0.012+)Σ=2.01O4. The crystal structures for igelströmite and manganoschafarzikite have been refined in space group P42/mbc from single-crystal X-ray diffraction data to R1 = 3.73 % and 1.51 %, respectively, giving the following sets of unit-cell parameters: a= 8.4856(2), 8.65159(8) Å; c= 6.0450(3), 5.97175(9); and V= 435.27(3), 446.986(11) Å3 for Z = 4. Both minerals are isostructural with minium, Pb4+Pb22+O4, where Pb4+O6 forms distorted octahedra, which connect via trans-edges to form rutile-like ribbons along c. The Pb2+ atoms appear in trigonal, flattened PbO3 pyramids, which are linked via corners to form zigzag (PbO2)n chains. The minium group, of general formula MX2O4(X= As3+, Sb3+, Pb2+), presently consists of the minerals minium, trippkeite, schafarzikite, igelströmite and manganoschafarzikite. For future new members, it is recommended to consider the X cation content for the root name and add prefixes to indicate the dominant metal at the M position.

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Section: Paragenesismentioning

confidence: 72%

Igelströmite, Fe³⁺(Sb³⁺Pb²⁺)O₄, and manganoschafarzikite, Mn²⁺Sb³⁺₂O₄, two new members of the newly established minium group, from the Långban Mn–Fe deposit, Värmland, Sweden

Holtstam,

Langhof,

Friis

et al. 2024

Eur. J. Mineral.

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“…probably in the range 200−400°C. Mineral formation probably took place in an alkaline environment, but not at such extreme high-pH conditions that are inferred to have prevailed in the ‘reduced veins’ characteristic for the late-stage D period at Långban (Boström, 2002).…”

Section: Occurrencementioning

confidence: 99%

Langhofite, Pb₂(OH)[WO₄(OH)], a new mineral from Långban, Sweden

Holtstam

Cámara

Karlsson

2020

MinMag

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Langhofite, ideally Pb2(OH)[WO4(OH)], is a new mineral from the Långban mine, Värmland, Sweden. The mineral and its name were approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA2019-005). It occurs in a small vug in hematite–pyroxene skarn associated with calcite, baryte, fluorapatite, mimetite and minor sulfide minerals. Langhofite is triclinic, space group P$\bar{1}$, and unit-cell parameters a = 6.6154(1) Å, b = 7.0766(1) Å, c = 7.3296(1) Å, α = 118.175(2)°, β = 94.451(1)°, γ = 101.146(1)° and V = 291.06(1) Å3 for Z = 2. The seven strongest Bragg peaks from powder X-ray diffractometry are [dobs, Å (I)(hkl)]: 6.04(24)(010), 3.26(22)(11$\bar{2}$), 3.181(19)(200), 3.079(24)(1$\bar{1}$2), 3.016(100)(020), 2.054(20)(3$\bar{1}$1) and 2.050(18)(13$\bar{2}$). Langhofite occurs as euhedral crystals up to 4 mm, elongated along the a axis, with lengthwise striation. Mohs hardness is ca. 2½, based on VHN25 data obtained in the range 130–192. The mineral is brittle, with perfect {010} and {100} cleavages. The calculated density based on the ideal formula is 7.95(1) g⋅cm–3. Langhofite is colourless to white (non-pleochroic) and transparent, with a white streak and adamantine lustre. Reflectance curves show normal dispersion, with maximum values 15.7–13.4% within 400–700 nm. Electron microprobe analyses yield only the metals Pb and W above the detection level. The presence of OH-groups is demonstrated with vibration spectroscopy, from band maxima present at ~3470 and 3330 cm–1. A distinct Raman peak at ca. 862 cm–1 is related to symmetric W–oxygen stretching vibrations. The crystal structure is novel and was refined to R = 1.6%. It contains [W2O8(OH)2]6– edge-sharing dimers (with highly distorted WO6-octahedra) forming chains along [101] with [(OH)2Pb4]6+ dimers formed by (OH)Pb3 triangles. Chains configure (010) layers linked along [010] by long and weak Pb–O bonds, thus explaining the observed perfect cleavage on {010}. The mineral is named for curator Jörgen Langhof (b. 1965), who collected the discovery sample.

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Late hydrothermal events at LÅngban – how many and how alkaline?

Cited by 2 publications

References 13 publications

Igelströmite, Fe³⁺(Sb³⁺Pb²⁺)O₄, and manganoschafarzikite, Mn²⁺Sb³⁺₂O₄, two new members of the newly established minium group, from the Långban Mn–Fe deposit, Värmland, Sweden

Igelströmite, Fe³⁺(Sb³⁺Pb²⁺)O₄, and manganoschafarzikite, Mn²⁺Sb³⁺₂O₄, two new members of the newly established minium group, from the Långban Mn–Fe deposit, Värmland, Sweden

Langhofite, Pb₂(OH)[WO₄(OH)], a new mineral from Långban, Sweden

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Late hydrothermal events at LÅngban – how many and how alkaline?

Cited by 2 publications

References 13 publications

Igelströmite, Fe3+(Sb3+Pb2+)O4, and manganoschafarzikite, Mn2+Sb3+2O4, two new members of the newly established minium group, from the Långban Mn–Fe deposit, Värmland, Sweden

Igelströmite, Fe3+(Sb3+Pb2+)O4, and manganoschafarzikite, Mn2+Sb3+2O4, two new members of the newly established minium group, from the Långban Mn–Fe deposit, Värmland, Sweden

Langhofite, Pb2(OH)[WO4(OH)], a new mineral from Långban, Sweden

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Igelströmite, Fe³⁺(Sb³⁺Pb²⁺)O₄, and manganoschafarzikite, Mn²⁺Sb³⁺₂O₄, two new members of the newly established minium group, from the Långban Mn–Fe deposit, Värmland, Sweden

Igelströmite, Fe³⁺(Sb³⁺Pb²⁺)O₄, and manganoschafarzikite, Mn²⁺Sb³⁺₂O₄, two new members of the newly established minium group, from the Långban Mn–Fe deposit, Värmland, Sweden

Langhofite, Pb₂(OH)[WO₄(OH)], a new mineral from Långban, Sweden