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Recognition and app...
Recognition and approval of potassic-richerite, an amphibole supergroup mineral, from the Pajsberg mines, Filipstad, Sweden.
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- Holtstam, Dan, 1963- (författare)
- Naturhistoriska riksmuseet,Enheten för geovetenskap
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- Cámara, Fernando, 1967- (författare)
- Università degli Studi di Milano
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- Skogby, Henrik, 1956- (författare)
- Naturhistoriska riksmuseet,Enheten för geovetenskap
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- Karlsson, Andreas (författare)
- Naturhistoriska riksmuseet,Enheten för geovetenskap
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- Langhof, Jörgen, 1965- (författare)
- Naturhistoriska riksmuseet,Enheten för geovetenskap
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(creator_code:org_t)
- 2018-08-10
- 2019
- Engelska.
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Ingår i: Mineralogy and Petrology. - : Springer. - 0930-0708 .- 1438-1168. ; 113, s. 7-16
- Relaterad länk:
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https://doi.org/10.1...
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https://link.springe...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Potassic-richterite, ideally AKB(NaCa)CMg5TSi8O22W(OH)2, is recognized as a valid member of the amphibole supergroup (IMA CNMNC 2017–102). Type material is from the Pajsberg Mn-Fe ore field, Filipstad, Värmland, Sweden, where the mineral occurs in a Mn-rich skarn, closely associated with mainly phlogopite, jacobsite and tephroite. The megascopic colour is straw yellow to grayish brown and the luster vitreous. The nearly anhedral crystals, up to 4 mm in length, are pale yellow (non-pleochroic) in thin section andoptically biaxial (−), with α = 1.615(5), β = 1.625(5), γ = 1.635(5). The calculated density is 3.07 g·cm−1. VHN100 is in the range 610–946. Cleavage is perfect along {110}. EPMA analysis in combination with Mössbauer and infrared spectroscopy yields the empirical formula (K0.61Na0.30Pb0.02)Σ0.93(Na1.14Ca0.79Mn0.07)Σ2(Mg4.31Mn0.47Fe3+0.20)Σ5(Si7.95Al0.04Fe3+0.01)Σ8O22(OH1.82F0.18)Σ2 for a fragmentused for collection of single-crystal X-ray diffraction data. The infra-red spectra show absorption bands at 3672 cm−1 and 3736 cm−1 for the α direction. The crystal structure was refined in space group C2/m to R1=3.6% [I >2σ(I)], with resulting cellparameters a = 9.9977(3) Å, b = 18.0409(4) Å, c = 5.2794(2) Å, γ = 104.465(4)°, V = 922.05(5) Å3 and Z=2. The A and M(4) sites split into A(m) (K+), A(2/m) (Na+), A(2) (Pb2+), and M(4′) (Mn2+) subsites, respectively. The remaining Mn2+ is strongly ordered at theoctahedrally coordinated M(2) site, possibly together with most of Fe3+. The skarn bearing potassic-richterite formed at peak metamorphism, under conditions of low SiO2 and Al2O3 activities and relatively high oxygen fugacities.
Ämnesord
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geologi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geology (hsv//eng)
Nyckelord
- Potassic-richterite
- Amphibole supergroup
- Crystal structure
- Skarn
- Pajsberg
- Långban-type deposit
- kali-richterit
- amfibol
- kristallstruktur
- skarn
- Pajsberg
- Långban-typ
- The changing Earth
- Den föränderliga jorden
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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