TY - JOUR

T1 - Coupled substitutions in natural MnO(OH) polymorphs

T2 - Infrared spectroscopic investigation

AU - Chukanov, Nikita V.

AU - Varlamov, Dmitry A.

AU - Pekov, Igor V.

AU - Zubkova, Natalia V.

AU - Kasatkin, Anatoly V.

AU - Britvin, Sergey N.

N1 - Chukanov, N.V.; Varlamov, D.A.; Pekov, I.V.; Zubkova, N.V.; Kasatkin, A.V.; Britvin, S.N. Coupled Substitutions in Natural MnO(OH) Polymorphs: Infrared Spectroscopic Investigation. Minerals 2021, 11, 969. https://doi.org/10.3390/min11090969

PY - 2021/9/6

Y1 - 2021/9/6

N2 - Solid solutions involving natural Mn3+O(OH) polymorphs, groutite, manganite, and feitknechtite are characterized and discussed based on original and literature data on the chemical composition, powder and single-crystal X-ray diffraction, and middle-range IR absorption spectra of these minerals. It is shown that manganite forms two kinds of solid-solution series, in which intermediate members have the general formulae (i) (Mn4+, Mn3+)O(OH,O), with pyrolusite as the Mn4+O2 end-member, and (ii) (Mn3+, M2+)O(OH, H2O), where M = Mn or Zn. In Zn-substituted man-ganite from Kapova Cave, South Urals, Russia, the Zn2+:Mn3+ ratio reaches 1:1 (the substitution of Mn3+ with Zn2+ is accompanied by the coupled substitution of OH− with H2O). Groutite forms solid-solution series with ramsdellite Mn4+O2. In addition, the incorporation of OH− anions in the 1 × 2 tunnels of ramsdellite is possible. Feitknechtite is considered to be isostructural with (or structurally related to) the compounds (M2+, Mn3+)(OH, O)2 (M = Mn, Zn) with a pyrochroite-related layered structure.

AB - Solid solutions involving natural Mn3+O(OH) polymorphs, groutite, manganite, and feitknechtite are characterized and discussed based on original and literature data on the chemical composition, powder and single-crystal X-ray diffraction, and middle-range IR absorption spectra of these minerals. It is shown that manganite forms two kinds of solid-solution series, in which intermediate members have the general formulae (i) (Mn4+, Mn3+)O(OH,O), with pyrolusite as the Mn4+O2 end-member, and (ii) (Mn3+, M2+)O(OH, H2O), where M = Mn or Zn. In Zn-substituted man-ganite from Kapova Cave, South Urals, Russia, the Zn2+:Mn3+ ratio reaches 1:1 (the substitution of Mn3+ with Zn2+ is accompanied by the coupled substitution of OH− with H2O). Groutite forms solid-solution series with ramsdellite Mn4+O2. In addition, the incorporation of OH− anions in the 1 × 2 tunnels of ramsdellite is possible. Feitknechtite is considered to be isostructural with (or structurally related to) the compounds (M2+, Mn3+)(OH, O)2 (M = Mn, Zn) with a pyrochroite-related layered structure.

KW - Feitknechtite

KW - Groutite

KW - IR spectroscopy

KW - Isomorphism

KW - Kapova Cave

KW - Manganite

KW - MnO(OH) polymorphs

KW - Pigment

KW - Solid solution

KW - South Urals

UR - http://www.scopus.com/inward/record.url?scp=85114285138&partnerID=8YFLogxK

U2 - 10.3390/min11090969

DO - 10.3390/min11090969

M3 - Article

AN - SCOPUS:85114285138

VL - 11

JO - Minerals

JF - Minerals

SN - 2075-163X

IS - 9

M1 - 969

ER -