Ferro-papikeite, ideally NaFe22+(Fe32+Al2)(Si5Al3)O22(OH)2, a new orthorhombic amphibole from Nordmark (Western Bergslagen), Sweden: Description and crystal structure

Frank C. Hawthorne; Maxwell C. Day; Mostafa Fayek; Kees Linthout; Wim J. Lustenhouwer; Roberta Oberti

doi:10.2138/am-2021-7877

Ferro-papikeite, ideally NaFe₂²⁺(Fe₃²⁺Al₂)(Si₅Al₃)O₂₂(OH)₂, a new orthorhombic amphibole from Nordmark (Western Bergslagen), Sweden: Description and crystal structure

Frank C. Hawthorne^*
, Maxwell C. Day
, Mostafa Fayek
, Kees Linthout
, Wim J. Lustenhouwer
, Roberta Oberti

^*Corresponding author for this work

Geology and Geochemistry

Research output: Contribution to Journal › Article › Academic › peer-review

Abstract

Ferro-papikeite, ideally NaFe22+(Fe32+Al2)(Si5Al3)O22(OH)2, is a new mineral of the amphibole supergroup from the Filipstad Municipality, Värmland County, Central Sweden, where it occurs in a medium-grade felsic metavolcanic rock. Ferro-papikeite is pale brown with a translucent luster, has a colorless to very pale-brown streak, and shows no fluorescence under long-wave or short-wave ultraviolet light. Grains are subhedral, 0.4-3.0 mm in size, and show well-developed {210} cleavage. It has a Mohs hardness of ~6 and is brittle with a splintery fracture, has the characteristic perfect {210} cleavage of orthorhombic amphiboles, intersecting at ∼56°, and the calculated density is 3.488 g/cm3. In transmitted plane-polarized light, ferro-papikeite is moderately pleochroic X = very pale brown, Y = Z = honey brown; X < Y = Z. Ferro-papikeite is biaxial (+), α = 1.674(2), β = 1.692(2), γ= 1.716(2), 2Vmeas = 86.2(9) and 2Vcalc = 88.3°, dispersion is r < v, weak. The orientation is: X || a, Y || b, Z || c. Ferro-papikeite is orthorhombic, space group Pnma, a = 18.628(4), b = 17.888(4), c = 5.3035(11) Å, V = 1767.2(6) Å3, Z = 4. The strongest ten X-ray diffraction lines in the powder pattern are [d in Å(I) (hkl)]: 8.255(100)(210), 3.223(39)(440), 3.057(68)(610), 2.824(28)(251), 2.674(41)(351), 2.572(56) (161,621), 2.549(38)(202), 2.501(50)(261,451), 2.158(25)(502), and 1.991(31)(661). Chemical analysis by electron microprobe gave SiO2 36.50, Al2O3 22.24, TiO2 0.09, FeO 31.54, MnO 0.65, MgO 5.48, CaO 0.08, Na2O 2.35, F 0.22, H2Ocalc 1.85, O=F -0.09, sum 100.91 wt%. The formula unit, calculated on the basis of 24 (O+OH+F) with (OH) = 2 apfu and Fe3+ = 0.13 apfu (determined from the <M2-O> distance) is A(Na0.70Ca0.01)B+C(Mg1.25Fe23.90+ Mn20.08+ Al1.62Fe30.13+ Ti40.01+)ς6.99T(Si5.60Al2.40)ς8O22(OH1.89F0.11)2. The crystal structure of ferro-papikeite was refined to an R-index of 3.60% using 2335 unique observed reflections collected with MoKa X-radiation. [4]Al3+ is ordered over the four T sites as follows: T 1B > T1A > T2B >> T2a, [6]Al3+ is completely ordered at M2, and Fe2+ is strongly ordered at M4. The A site is split with Na+ strongly ordered at A1. End-member ferro-papikeite is related to end-member gedrite, □Mg2(Mg3Al2)(Si6Al2)O22(OH)2, by the substitutions Na+ → □, Fe2+ → Mg, and Al3+ → Si4+. The description of ferro-papikeite as a new species further emphasizes the compositional similarities between the monoclinic calcium amphiboles and the orthorhombic magnesium-iron-manganese amphiboles.

Original language	English
Pages (from-to)	306-312
Number of pages	7
Journal	American Mineralogist
Volume	107
Issue number	2
Early online date	1 Feb 2022
DOIs	https://doi.org/10.2138/am-2021-7877
Publication status	Published - Feb 2022

Bibliographical note

Funding Information:
We thank John Hughes and Gordon Brown, Jr. for their very good comments on this paper. We thank Alfredo Camacho, Department of Geological Sciences, University of Manitoba, for arranging for thin sections to be cut, and for help with the thin-section photography and interpretation. This work was supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant, and by Canada Foundation for Innovation grants to F.C.H.

Publisher Copyright:
© 2022 Mineralogical Society of America.

Funding

We thank John Hughes and Gordon Brown, Jr. for their very good comments on this paper. We thank Alfredo Camacho, Department of Geological Sciences, University of Manitoba, for arranging for thin sections to be cut, and for help with the thin-section photography and interpretation. This work was supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant, and by Canada Foundation for Innovation grants to F.C.H.

Keywords

Bergslagen, Sweden
crystal-structure refinement
electron-microprobe analysis
Ferro-papikeite
new amphibole
optical properties

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10.2138/am-2021-7877

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Cite this

@article{1fa9c695e436488dbae8ad3dd53ad4d6,

title = "Ferro-papikeite, ideally NaFe22+(Fe32+Al2)(Si5Al3)O22(OH)2, a new orthorhombic amphibole from Nordmark (Western Bergslagen), Sweden: Description and crystal structure",

abstract = "Ferro-papikeite, ideally NaFe22+(Fe32+Al2)(Si5Al3)O22(OH)2, is a new mineral of the amphibole supergroup from the Filipstad Municipality, V{\"a}rmland County, Central Sweden, where it occurs in a medium-grade felsic metavolcanic rock. Ferro-papikeite is pale brown with a translucent luster, has a colorless to very pale-brown streak, and shows no fluorescence under long-wave or short-wave ultraviolet light. Grains are subhedral, 0.4-3.0 mm in size, and show well-developed \{210\} cleavage. It has a Mohs hardness of \textasciitilde{}6 and is brittle with a splintery fracture, has the characteristic perfect \{210\} cleavage of orthorhombic amphiboles, intersecting at ∼56°, and the calculated density is 3.488 g/cm3. In transmitted plane-polarized light, ferro-papikeite is moderately pleochroic X = very pale brown, Y = Z = honey brown; X < Y = Z. Ferro-papikeite is biaxial (+), α = 1.674(2), β = 1.692(2), γ= 1.716(2), 2Vmeas = 86.2(9) and 2Vcalc = 88.3°, dispersion is r < v, weak. The orientation is: X || a, Y || b, Z || c. Ferro-papikeite is orthorhombic, space group Pnma, a = 18.628(4), b = 17.888(4), c = 5.3035(11) {\AA}, V = 1767.2(6) {\AA}3, Z = 4. The strongest ten X-ray diffraction lines in the powder pattern are [d in {\AA}(I) (hkl)]: 8.255(100)(210), 3.223(39)(440), 3.057(68)(610), 2.824(28)(251), 2.674(41)(351), 2.572(56) (161,621), 2.549(38)(202), 2.501(50)(261,451), 2.158(25)(502), and 1.991(31)(661). Chemical analysis by electron microprobe gave SiO2 36.50, Al2O3 22.24, TiO2 0.09, FeO 31.54, MnO 0.65, MgO 5.48, CaO 0.08, Na2O 2.35, F 0.22, H2Ocalc 1.85, O=F -0.09, sum 100.91 wt\%. The formula unit, calculated on the basis of 24 (O+OH+F) with (OH) = 2 apfu and Fe3+ = 0.13 apfu (determined from the distance) is A(Na0.70Ca0.01)B+C(Mg1.25Fe23.90+ Mn20.08+ Al1.62Fe30.13+ Ti40.01+)ς6.99T(Si5.60Al2.40)ς8O22(OH1.89F0.11)2. The crystal structure of ferro-papikeite was refined to an R-index of 3.60\% using 2335 unique observed reflections collected with MoKa X-radiation. [4]Al3+ is ordered over the four T sites as follows: T 1B > T1A > T2B >> T2a, [6]Al3+ is completely ordered at M2, and Fe2+ is strongly ordered at M4. The A site is split with Na+ strongly ordered at A1. End-member ferro-papikeite is related to end-member gedrite, □Mg2(Mg3Al2)(Si6Al2)O22(OH)2, by the substitutions Na+ → □, Fe2+ → Mg, and Al3+ → Si4+. The description of ferro-papikeite as a new species further emphasizes the compositional similarities between the monoclinic calcium amphiboles and the orthorhombic magnesium-iron-manganese amphiboles. ",

keywords = "Bergslagen, Sweden, crystal-structure refinement, electron-microprobe analysis, Ferro-papikeite, new amphibole, optical properties",

author = "Hawthorne, \{Frank C.\} and Day, \{Maxwell C.\} and Mostafa Fayek and Kees Linthout and Lustenhouwer, \{Wim J.\} and Roberta Oberti",

note = "Funding Information: We thank John Hughes and Gordon Brown, Jr. for their very good comments on this paper. We thank Alfredo Camacho, Department of Geological Sciences, University of Manitoba, for arranging for thin sections to be cut, and for help with the thin-section photography and interpretation. This work was supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant, and by Canada Foundation for Innovation grants to F.C.H. Publisher Copyright: {\textcopyright} 2022 Mineralogical Society of America.",

year = "2022",

month = feb,

doi = "10.2138/am-2021-7877",

language = "English",

volume = "107",

pages = "306--312",

journal = "American Mineralogist",

issn = "0003-004X",

publisher = "Walter de Gruyter GmbH",

number = "2",

}

Ferro-papikeite, ideally NaFe₂²⁺(Fe₃²⁺Al₂)(Si₅Al₃)O₂₂(OH)₂, a new orthorhombic amphibole from Nordmark (Western Bergslagen), Sweden: Description and crystal structure. / Hawthorne, Frank C.; Day, Maxwell C.; Fayek, Mostafa et al.
In: American Mineralogist, Vol. 107, No. 2, 02.2022, p. 306-312.

Research output: Contribution to Journal › Article › Academic › peer-review

TY - JOUR

T1 - Ferro-papikeite, ideally NaFe22+(Fe32+Al2)(Si5Al3)O22(OH)2, a new orthorhombic amphibole from Nordmark (Western Bergslagen), Sweden: Description and crystal structure

AU - Hawthorne, Frank C.

AU - Day, Maxwell C.

AU - Fayek, Mostafa

AU - Linthout, Kees

AU - Lustenhouwer, Wim J.

AU - Oberti, Roberta

N1 - Funding Information: We thank John Hughes and Gordon Brown, Jr. for their very good comments on this paper. We thank Alfredo Camacho, Department of Geological Sciences, University of Manitoba, for arranging for thin sections to be cut, and for help with the thin-section photography and interpretation. This work was supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant, and by Canada Foundation for Innovation grants to F.C.H. Publisher Copyright: © 2022 Mineralogical Society of America.

PY - 2022/2

Y1 - 2022/2

N2 - Ferro-papikeite, ideally NaFe22+(Fe32+Al2)(Si5Al3)O22(OH)2, is a new mineral of the amphibole supergroup from the Filipstad Municipality, Värmland County, Central Sweden, where it occurs in a medium-grade felsic metavolcanic rock. Ferro-papikeite is pale brown with a translucent luster, has a colorless to very pale-brown streak, and shows no fluorescence under long-wave or short-wave ultraviolet light. Grains are subhedral, 0.4-3.0 mm in size, and show well-developed {210} cleavage. It has a Mohs hardness of ~6 and is brittle with a splintery fracture, has the characteristic perfect {210} cleavage of orthorhombic amphiboles, intersecting at ∼56°, and the calculated density is 3.488 g/cm3. In transmitted plane-polarized light, ferro-papikeite is moderately pleochroic X = very pale brown, Y = Z = honey brown; X < Y = Z. Ferro-papikeite is biaxial (+), α = 1.674(2), β = 1.692(2), γ= 1.716(2), 2Vmeas = 86.2(9) and 2Vcalc = 88.3°, dispersion is r < v, weak. The orientation is: X || a, Y || b, Z || c. Ferro-papikeite is orthorhombic, space group Pnma, a = 18.628(4), b = 17.888(4), c = 5.3035(11) Å, V = 1767.2(6) Å3, Z = 4. The strongest ten X-ray diffraction lines in the powder pattern are [d in Å(I) (hkl)]: 8.255(100)(210), 3.223(39)(440), 3.057(68)(610), 2.824(28)(251), 2.674(41)(351), 2.572(56) (161,621), 2.549(38)(202), 2.501(50)(261,451), 2.158(25)(502), and 1.991(31)(661). Chemical analysis by electron microprobe gave SiO2 36.50, Al2O3 22.24, TiO2 0.09, FeO 31.54, MnO 0.65, MgO 5.48, CaO 0.08, Na2O 2.35, F 0.22, H2Ocalc 1.85, O=F -0.09, sum 100.91 wt%. The formula unit, calculated on the basis of 24 (O+OH+F) with (OH) = 2 apfu and Fe3+ = 0.13 apfu (determined from the distance) is A(Na0.70Ca0.01)B+C(Mg1.25Fe23.90+ Mn20.08+ Al1.62Fe30.13+ Ti40.01+)ς6.99T(Si5.60Al2.40)ς8O22(OH1.89F0.11)2. The crystal structure of ferro-papikeite was refined to an R-index of 3.60% using 2335 unique observed reflections collected with MoKa X-radiation. [4]Al3+ is ordered over the four T sites as follows: T 1B > T1A > T2B >> T2a, [6]Al3+ is completely ordered at M2, and Fe2+ is strongly ordered at M4. The A site is split with Na+ strongly ordered at A1. End-member ferro-papikeite is related to end-member gedrite, □Mg2(Mg3Al2)(Si6Al2)O22(OH)2, by the substitutions Na+ → □, Fe2+ → Mg, and Al3+ → Si4+. The description of ferro-papikeite as a new species further emphasizes the compositional similarities between the monoclinic calcium amphiboles and the orthorhombic magnesium-iron-manganese amphiboles.

AB - Ferro-papikeite, ideally NaFe22+(Fe32+Al2)(Si5Al3)O22(OH)2, is a new mineral of the amphibole supergroup from the Filipstad Municipality, Värmland County, Central Sweden, where it occurs in a medium-grade felsic metavolcanic rock. Ferro-papikeite is pale brown with a translucent luster, has a colorless to very pale-brown streak, and shows no fluorescence under long-wave or short-wave ultraviolet light. Grains are subhedral, 0.4-3.0 mm in size, and show well-developed {210} cleavage. It has a Mohs hardness of ~6 and is brittle with a splintery fracture, has the characteristic perfect {210} cleavage of orthorhombic amphiboles, intersecting at ∼56°, and the calculated density is 3.488 g/cm3. In transmitted plane-polarized light, ferro-papikeite is moderately pleochroic X = very pale brown, Y = Z = honey brown; X < Y = Z. Ferro-papikeite is biaxial (+), α = 1.674(2), β = 1.692(2), γ= 1.716(2), 2Vmeas = 86.2(9) and 2Vcalc = 88.3°, dispersion is r < v, weak. The orientation is: X || a, Y || b, Z || c. Ferro-papikeite is orthorhombic, space group Pnma, a = 18.628(4), b = 17.888(4), c = 5.3035(11) Å, V = 1767.2(6) Å3, Z = 4. The strongest ten X-ray diffraction lines in the powder pattern are [d in Å(I) (hkl)]: 8.255(100)(210), 3.223(39)(440), 3.057(68)(610), 2.824(28)(251), 2.674(41)(351), 2.572(56) (161,621), 2.549(38)(202), 2.501(50)(261,451), 2.158(25)(502), and 1.991(31)(661). Chemical analysis by electron microprobe gave SiO2 36.50, Al2O3 22.24, TiO2 0.09, FeO 31.54, MnO 0.65, MgO 5.48, CaO 0.08, Na2O 2.35, F 0.22, H2Ocalc 1.85, O=F -0.09, sum 100.91 wt%. The formula unit, calculated on the basis of 24 (O+OH+F) with (OH) = 2 apfu and Fe3+ = 0.13 apfu (determined from the distance) is A(Na0.70Ca0.01)B+C(Mg1.25Fe23.90+ Mn20.08+ Al1.62Fe30.13+ Ti40.01+)ς6.99T(Si5.60Al2.40)ς8O22(OH1.89F0.11)2. The crystal structure of ferro-papikeite was refined to an R-index of 3.60% using 2335 unique observed reflections collected with MoKa X-radiation. [4]Al3+ is ordered over the four T sites as follows: T 1B > T1A > T2B >> T2a, [6]Al3+ is completely ordered at M2, and Fe2+ is strongly ordered at M4. The A site is split with Na+ strongly ordered at A1. End-member ferro-papikeite is related to end-member gedrite, □Mg2(Mg3Al2)(Si6Al2)O22(OH)2, by the substitutions Na+ → □, Fe2+ → Mg, and Al3+ → Si4+. The description of ferro-papikeite as a new species further emphasizes the compositional similarities between the monoclinic calcium amphiboles and the orthorhombic magnesium-iron-manganese amphiboles.

KW - Bergslagen, Sweden

KW - crystal-structure refinement

KW - electron-microprobe analysis

KW - Ferro-papikeite

KW - new amphibole

KW - optical properties

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