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Fenaksite

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Formula:
(K,Na)4(Fe,Mn)2(Si4O10)2(OH,F)
Hardness:
5 - 5½
Crystal System:
Triclinic
Name:
Named for its chemical composition (Fe, Na, K, Si).
This page provides mineralogical data about Fenaksite.


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Classification of FenaksiteHide

Approved
9.DG.70

9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
70.1.1.2

70 : INOSILICATES Column or Tube Structures
1 : Column or Tube Structures with columnar silicate units
14.20.8

14 : Silicates not Containing Aluminum
20 : Silicates of Fe and alkali metals

Physical Properties of FenaksiteHide

Hardness:
5 - 5½ on Mohs scale

Optical Data of FenaksiteHide

Type:
Biaxial (+)
RI values:
nα = 1.541 nβ = 1.560 nγ = 1.567
2V:
Measured: 84° , Calculated: 60°
Max Birefringence:
δ = 0.026
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Low
Dispersion:
weak

Chemical Properties of FenaksiteHide

Formula:
(K,Na)4(Fe,Mn)2(Si4O10)2(OH,F)
IMA Formula:
KNaFe2+Si4O10
Common Impurities:
Ti,Al,Mg

Crystallography of FenaksiteHide

Crystal System:
Triclinic
Cell Parameters:
a = 8.2 Å, b = 9.97 Å, c = 6.97 Å
α = 98.58°, β = 114.47°, γ = 105.02°
Ratio:
a:b:c = 0.822 : 1 : 0.699
Unit Cell V:
479.12 ų (Calculated from Unit Cell)

Type Occurrence of FenaksiteHide

Synonyms of FenaksiteHide

Other Language Names for FenaksiteHide

Relationship of Fenaksite to other SpeciesHide

Other Members of this group:
CalcinaksiteKNaCa(Si4O10)·H2OTric. 1 : P1
LitidioniteCuNaKSi4O10Tric.
ManaksiteKNaMnSi4O10Tric.

Common AssociatesHide

Associated Minerals Based on Photo Data:
Delhayelite3 photos of Fenaksite associated with Delhayelite on mindat.org.
Aenigmatite1 photo of Fenaksite associated with Aenigmatite on mindat.org.
Aegirine1 photo of Fenaksite associated with Aegirine on mindat.org.
Lamprophyllite1 photo of Fenaksite associated with Lamprophyllite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.DG.05BustamiteCaMn2+(Si2O6)Tric. 1 : P1
9.DG.05FerrobustamiteCaFe2+(Si2O6)Tric.
9.DG.05PectoliteNaCa2Si3O8(OH)Tric. 1 : P1
9.DG.05SeranditeNaMn2+2Si3O8(OH)Tric. 1 : P1
9.DG.05WollastoniteCaSiO3Tric. 1 : P1
9.DG.05Wollastonite-1ACaSiO3Tric.
9.DG.07CascanditeCa(Sc,Fe3+)(HSi3O9)Tric.
9.DG.08Plombièrite[Ca4Si6O16(OH)2 · 2H2O]·(Ca·5H2O)Orth.
9.DG.10Clinotobermorite[Ca4Si6O17 · 2H2O]·(Ca·3H2O)Mon.
9.DG.10RiversideiteCa5(HSi3O9)2 · 2H2OOrth.
9.DG.10Tobermorite[Ca4Si6O17 · 2H2O]·(Ca·3H2O)Orth.
9.DG.15FoshagiteCa4(Si3O9)(OH)2Tric.
9.DG.20JenniteCa9(Si3O9)2(OH)8 · 8H2OTric.
9.DG.25ParaumbiteK3Zr2H(Si3O9)2 · nH2OOrth.
9.DG.25UmbiteK2(Zr,Ti)Si3O9 · H2OOrth.
9.DG.30SørenseniteNa4SnBe2Si6O16(OH)4Mon. 2/m : B2/b
9.DG.35XonotliteCa6(Si6O17)(OH)2Mon. 2/m
9.DG.40HillebranditeCa2(SiO3)(OH)2Orth. mmm (2/m 2/m 2/m) : Cmcm
9.DG.45ZoriteNa8(Ti,Nb)5(Si6O17)2(OH,O)5 · 14H2OOrth.
9.DG.45ChivruaiiteCa4(Ti,Nb)5(Si6O17)2(OH,O)5 · 13-14H2OOrth. mmm (2/m 2/m 2/m) : Cmmm
9.DG.50Haineaultite(Na,Ca)5Ca(Ti,Nb)5(Si6O17)2(OH,F)8 · 5H2OOrth. 2 2 2 : C2 2 2
9.DG.55EpididymiteNa2Be2Si6O15 · H2OOrth. mmm (2/m 2/m 2/m) : Pnma
9.DG.60EudidymiteNa2Be2Si6O15 · H2OMon. 2/m : B2/b
9.DG.65ElpiditeNa2ZrSi6O15 · 3H2OOrth.
9.DG.70LitidioniteCuNaKSi4O10Tric.
9.DG.70ManaksiteKNaMnSi4O10Tric.
9.DG.75TinaksiteK2Na(Ca,Mn2+)2Ti[O|Si7O18(OH)]Tric.
9.DG.75TokkoiteK2Ca4[Si7O18(OH)](OH,F)Tric.
9.DG.75SenkevichiteCsKNaCa2Ti[O|Si7O18(OH)]Tric. 1 : P1
9.DG.80CanasiteK3Na3Ca5Si12O30(OH)4
9.DG.80FluorcanasiteK3Na3Ca5Si12O30F4 · H2OMon. m : Bm
9.DG.85MiseriteK1.5-x(Ca,Y,REE)5(Si6O15)(Si2O7)(OH,F)2 · yH2OTric.
9.DG.90FrankameniteK3Na3Ca5(Si12O30)(F,OH)4 · H2OTric.
9.DG.92Charoite(K,Sr)15-16(Ca,Na)32[Si6O11(O,OH)6]2[Si12O18(O,OH)12]2[Si17O25(O,OH)18]2(OH,F)4 · ~3H2OMon. 2/m : P21/m
9.DG.95YuksporiteK4(Ca,Na)14(Sr,Ba)2(◻,Mn,Fe)(Ti,Nb)4(O,OH)4(Si6O17)2(Si2O7)3(H2O,OH)3Orth.
9.DG.97Eveslogite(Na,K,Ca,Sr,Ba)48 [(Ti,Nb,Mn,Fe2+)12Si48O144(OH)12](F,OH,Cl)14Mon. 2/m : P2/m

Related Minerals - Dana Grouping (8th Ed.)Hide

70.1.1.1LitidioniteCuNaKSi4O10Tric.
70.1.1.3ManaksiteKNaMnSi4O10Tric.
70.1.1.4AgrelliteNaCa2Si4O10FTric.

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

14.20.1EmeleusiteLi2Na4Fe2Si12O30Orth.
14.20.2AegirineNaFe3+Si2O6Mon. 2/m : B2/b
14.20.4WilkinsoniteNa2Fe2+4Fe3+2(Si6O18)O2Tric. 1 : P1
14.20.5TuperssuatsiaiteNa2Fe3Si8O20(OH)2 · 4H2OMon. 2/m : B2/m
14.20.6Riebeckite◻[Na2][Fe2+3Fe3+2]Si8O22(OH)2Mon. 2/m : B2/m
14.20.7 Ferri-anniteKFe2+3((Fe3+,Al)Si3O10)(OH)2
14.20.9Montdorite(K,Na)2(Fe2+,Mn2+,Mg)5(Si4O10)2(OH,F)4

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for FenaksiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
I.V. Rozhdestvenskaya, I.I. Bannova, L.V. Nikishova, and T.V. Soboleva (2004): The crystal structure of fenaksite K2Na2Fe2Si8O20. Transactions (Doklady) of the Russian Academy of Sciences/Earth Science Section, 398, 1029-1033.
American Mineralogist: 45: 252.
Trudy Mineralogicheskogo Muzeya Academii Nauk SSSR: 9: 152-157.
Doklady Akademii Nauk SSSR: 329: 212-215.
Acta Crystallographica: B33: 1071-1075.

Internet Links for FenaksiteHide

Localities for FenaksiteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Russia
 
  • Northern Region
    • Murmanskaya Oblast'
      • Khibiny Massif
        • Koashva Mt
Arzamastsev, A., Yakovenchuk, V., Pakhomovsky, Y., & Ivanyuk, G. (2008). The Khibina and Lovozero alkaline massifs: Geology and unique mineralization. In Guidbook for 33rd International Geological Congress Excursion (No. 47, p. 58).
Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
[World of Stones 95:5-6, p64]
Takai, Y., Uehara, S., Inoo, T. (2011) Minerals from Khibiny, Kola, Russia. Chigaku Kenkyu, 60 (1), 41-46.; Arzamastsev, A., Yakovenchuk, V., Pakhomovsky, Y., & Ivanyuk, G. (2008). The Khibina and Lovozero alkaline massifs: Geology and unique mineralization. In Guidbook for 33rd International Geological Congress Excursion (No. 47, p. 58).
O Dziallas collection; Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
          • Rasvumchorr Mine
Sokolova et al (2005) New Data on Minerals Vol 40 pp115-118; Pekov I.V., Zubkova N.V., Filinchuk Ya.E., Chukanov N.V., Zadov A.E., Pushcharovsky D.Yu., Gobechiya E.R. (2010): Shlykovite, KCa[Si4O9(OH)]·3H2O, and cryptophyllite, K2Ca[Si4O10]·5H2O, two new mineral species from the Khibiny alkaline complex, Kola Peninsula, Russia. Zapiski RMO, 139(1), 37-50.
Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
        • Yukspor Mt
Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
Mineral and/or Locality  
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