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Fenaksite

A valid IMA mineral species
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02258820014946849909494.jpg
Fenaksite

Koashva Open Pit, Koashva Mt, Khibiny Massif, Murmansk Oblast, Russia
02341390014946850329019.jpg
Fenaksite, etc.

Rasvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia
04240400014946850298673.jpg
Fenaksite

Rasvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia
02258820014946849909494.jpg
Fenaksite

Koashva Open Pit, Koashva Mt, Khibiny Massif, Murmansk Oblast, Russia
06554290014956818681828.jpg
Fenaksite, etc.

Rasvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia
04240400014946850298673.jpg
Fenaksite

Rasvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia
02258820014946849909494.jpg
Fenaksite

Koashva Open Pit, Koashva Mt, Khibiny Massif, Murmansk Oblast, Russia
02341390014946850329019.jpg
Fenaksite, etc.

Rasvumchorr Mt, Khibiny Massif, Murmansk Oblast, Russia
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About FenaksiteHide

Formula:
(K,Na)4(Fe,Mn)2(Si4O10)2(OH,F)
Colour:
Light rose
Lustre:
Pearly
Hardness:
5 - 5½
Specific Gravity:
2.744
Crystal System:
Triclinic
Name:
Named for its chemical composition (Fe, Na, K, Si).
The iron analogue of manaksite.


Unique IdentifiersHide

Mindat ID:
1475
Long-form identifier:
mindat:1:1:1475:1
GUID
(UUID V4):
df916e80-81a1-445f-b7f8-2fbd81bff232

IMA Classification of FenaksiteHide

Classification of FenaksiteHide

Strunz-mindat (2024):
9.DG.70

9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains
Dana 8th ed.:
70.1.1.2

70 : INOSILICATES Column or Tube Structures
1 : Column or Tube Structures with columnar silicate units
Hey's CIM Ref.:
14.20.8

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

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

SymbolSourceReference
FnkIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43

Physical Properties of FenaksiteHide

Lustre:
Pearly
Transparency:
Transparent, Translucent
Comment:
On cleavages
Colour:
Light rose
Hardness:
5 - 5½ on Mohs scale
Cleavage:
Distinct/Good
Two, intersecting at an angle of 122 degrees.
Density:
2.744 g/cm3 (Measured)    2.74 g/cm3 (Calculated)

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

Chemistry of FenaksiteHide

Mindat Formula:
(K,Na)4(Fe,Mn)2(Si4O10)2(OH,F)
Elements listed:
F, Fe, H, K, Mn, Na, O, Si - search for minerals with similar chemistry
Common Impurities:
Ti,Al,Mg

Crystallography of FenaksiteHide

Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 8.24 Å, b = 9.97 Å, c = 6.97 Å
α = 98.58°, β = 114.47°, γ = 105.02°
Ratio:
a:b:c = 0.826 : 1 : 0.699
Unit Cell V:
481.46 ų (Calculated from Unit Cell)
Z:
2

Crystal StructureHide

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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0012511FenaksiteRozhdestvenskaya I V, Bannova I I, Nikishova L V, Soboleva T V (2004) The crystal structure of fenaksite K2Na2Fe2Si8O20 Doklady Earth Sciences 398 1029-10332004synthetic0293
0019813FenaksiteBrandao P, Rocha J, Reis M S, dos Santos A M, Jin R (2009) Magnetic properties of KNaMSi4O10 compounds (M=Mn,Fe,Cu) Journal of Solid State Chemistry 182 253-2582009synthetic0293
0015598FenaksiteGolovachev V P, Drozdov Y N, Kuz'min E A, Belov N V (1971) The crystal structure of phenaxite FeNaK(Si4O10)(KNaFe[Si4O10]) Soviet Physics Doklady 15 902-9041971Khibiny massif, Kola Peninsula, Russia0293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
3.03 Å(100)
3.55 Å(70)
3.44 Å(70)
2.46 Å(70)
2.88 Å(60)
2.71 Å(60)
1.875 Å(60)

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Stage 4b: Highly evolved igneous rocks>3.0
35 : Ultra-alkali and agpaitic igneous rocks

Type Occurrence of FenaksiteHide

Type Locality:
ⓘ Material'naya Adit, Yukspor Mt, Khibiny Massif, Murmansk Oblast, Russia
General Appearance of Type Material:
Grains up to 2-4 cm in diameter.
Place of Conservation of Type Material:
Geology Museum, Kola Branch, Academy of Sciences, Apatity, 1780; Vernadsky Geological Museum, Moscow, 46626; A.E. Fersman Mineralogical Museum, Academy of Sciences, Moscow, Russia, 61123, 61124, 62013.
Associated Minerals at Type Locality:
NephelineEudialyteDelhayeliteAlbiteAegirine-augite
Reference:
Dorfman M D, Rogachev D D, Goroshchenko Z I, Mokretsova A V (1959) Fenaksite - a new mineral. Trudy Mineralogicheskogo Muzeya Akademiya Nauk SSSR 9, 152-157

Synonyms of FenaksiteHide

Other Language Names for FenaksiteHide

Relationship of Fenaksite to other SpeciesHide

Member of:
Litidionite Group
Other Members of this group:
CalcinaksiteKNaCa(Si4O10) · H2OTric. 1 : P1
EnricofrancoiteKNaCaSi4O10Tric. 1 : P1
LitidioniteCuNaKSi4O10Tric. 1 : P1
ManaksiteKNaMnSi4O10Tric. 1 : P1

Common AssociatesHide

Associated Minerals Based on Photo Data:
3 photos of Fenaksite associated with Delhayelite(Na,K)10Ca5Al6Si32O80(Cl2,F2,SO4)3 · 18H2O
1 photo of Fenaksite associated with AenigmatiteNa4[Fe2+10Ti2]O4[Si12O36]
1 photo of Fenaksite associated with AegirineNaFe3+Si2O6
1 photo of Fenaksite associated with Lamprophyllite(Na,Mn2+)3(Sr,Na)2(Ti,Fe3+)3(Si2O7)2O2(OH,O,F)2

Related Minerals - Strunz-mindat GroupingHide

9.DG.CalcinaksiteKNaCa(Si4O10) · H2OTric. 1 : P1
9.DG.Barrydawsonite-(Y)Na1.5Y0.5CaSi3O8(OH)Mon. 2/m : P21/b
9.DG.ParatobermoriteCa4(Al0.5Si0.5)2Si4O16(OH)(H2O)2 · (Ca · 3H2O)Mon. 2/m
9.DG.AlvesiteNaKZrSi6O15 · 2H2OOrth. mmm (2/m 2/m 2/m)
9.DG.02SteedeiteNaMn2[Si3BO9](OH)2Tric. 1 : P1
9.DG.02NolzeiteNaMn2[Si3BO9](OH)2 · 2H2OTric. 1 : P1
9.DG.05BustamiteCaMn2+(Si2O6)Tric. 1 : P1
9.DG.05FerrobustamiteCaFe2+(Si2O6)Tric. 1
9.DG.05PectoliteNaCa2Si3O8(OH)Tric. 1 : P1
9.DG.05SeranditeNaMn2+2Si3O8(OH)Tric. 1 : P1
9.DG.05WollastoniteCa3(Si3O9)Tric. 1 : P1
9.DG.05Wollastonite-1ACaSiO3Tric. 1 : P1
9.DG.05TanohataiteLiMn2Si3O8(OH)Tric. 1 : P1
9.DG.05SchizoliteNaCaMnSi3O8(OH)Tric. 1 : P1
9.DG.05MurakamiiteLiCa2Si3O8(OH)Tric. 1 : P1
9.DG.05DalnegorskiteCa5Mn(Si3O9)2Tric. 1 : P1
9.DG.07CascanditeCaScSi3O8(OH)Tric. 1
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.10TobermoriteCa4Si6O17(H2O)2 · (Ca · 3H2O)Mon. 2 : P21
9.DG.12JusiteNa2Ca15Al4Si16O54 · 17H2O
9.DG.12KenotobermoriteCa4Si6O15(OH)2(H2O)2 · 3H2OMon.
9.DG.15FoshagiteCa4(Si3O9)(OH)2Tric. 1 : P1
9.DG.20JenniteCa9(Si3O9)2(OH)8 · 8H2OTric. 1 : P1
9.DG.20KameneviteK2TiSi3O9 · H2OOrth. 2 2 2 : P21 21 21
9.DG.25ParaumbiteK3Zr2H(Si3O9)2 · nH2OOrth. mm2
9.DG.25UmbiteK2(Zr,Ti)Si3O9 · H2OOrth. 2 2 2 : P21 21 21
9.DG.30SørenseniteNa4SnBe2Si6O16(OH)4Mon. 2/m : B2/b
9.DG.32Escheite Ca2NaMnTi5[Si12O34]O2(OH)3 · 12H2OOrth. mm2 : Ama2
9.DG.35XonotliteCa6(Si6O17)(OH)2Mon. 2/m : B2/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.65PatyniteNaKCa4[Si9O23]Tric. 1 : P1
9.DG.67WhelaniteCu2+2Ca6[Si6O17(OH)](CO3)(OH)3 · 2H2OOrth. mm2 : Pnn2
9.DG.70LitidioniteCuNaKSi4O10Tric. 1 : P1
9.DG.70ManaksiteKNaMnSi4O10Tric. 1 : P1
9.DG.70YusupoviteNa2Zr(Si6O15) · 2.5H2OMon. 2/m : B2/m
9.DG.70EnricofrancoiteKNaCaSi4O10Tric. 1 : P1
9.DG.75TinaksiteK2Na(Ca,Mn2+)2TiO[Si7O18(OH)]Tric.
9.DG.75TokkoiteK2Ca4[Si7O18(OH)](OH,F)Tric.
9.DG.75SenkevichiteCsKNaCa2TiO[Si7O18](OH)Tric. 1 : P1
9.DG.80CanasiteK3Na3Ca5Si12O30(OH)4Mon. m : Bm
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. 1 : P1
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)3Mon. 2/m : P21/m
9.DG.97Eveslogite(Na,K,Ca,Sr,Ba)48 [(Ti,Nb,Mn,Fe2+)12Si48O144(OH)12](F,OH,Cl)14Mon. 2/m : P2/m

Other InformationHide

Notes:
Decomposed by acids with the deposition of silica.
Fuses easily before the blowpipe to a green glass; in a reducing flame, the powder becomes magnetic.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for FenaksiteHide

References 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 references and 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 (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.
Russia
 
  • Murmansk Oblast
    • Khibiny Massif
      • Koashva Mt
Arzamastsev et al. (2008)
Pekov (1998)
[World of Stones 95:5-6
Arzamastsev et al. (2008) +1 other reference
O Dziallas collection +1 other reference
        • Rasvumchorr Mine
Sokolova et al (2005) +1 other reference
Pekov (1998)
      • Yukspor Mt
Dorfman et al. (1959) +2 other references
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