Mineralogy Database

Fenaksite Mineral Data

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General Fenaksite Information

Help on Chemical  Formula: Chemical Formula: (K,Na,Ca)4(Fe++,Fe+++,Mn)2Si8O20(OH,F)
Help on Composition: Composition: Molecular Weight = 806.42 gm
   Potassium   8.73 %  K    10.51 % K2O
   Sodium      4.28 %  Na    5.76 % Na2O
   Calcium     3.48 %  Ca    4.87 % CaO
   Manganese   2.04 %  Mn    2.64 % MnO
   Iron       11.77 %  Fe   11.58 % FeO /  3.96 % Fe2O3
   Silicon    27.86 %  Si   59.61 % SiO2
   Hydrogen    0.10 %  H     0.89 % H2O
   Oxygen     41.27 %  O
   Fluorine    0.47 %  F     0.47 % F
                -   %   F    -0.20 % -O=F2    
             ______        ______ 
             100.00 %      100.10 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: K1.8Na1.5Ca0.7Fe2+1.3Fe3+0.4Mn2+0.3Si8O20(OH)0.8F0.2
Help on Environment: Environment: In pegmatites associated with an ijolite-urtite intrusion in a differentiated alkalic massif.
Help on IMA Status: IMA Status: Approved IMA 1959
Help on Locality: Locality: On Mts. Rasvumchorr and Yukspor, Khibiny massif, Kola Peninsula, Russia. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for the Fe, Na, K, and Si in the formula.
Help on Name Pronunciation: Name Pronunciation: Fenaksite + Pronunciation Say FENAKSITE
Help on Synonym: Synonym: ICSD 20098
  PDF 13-520
 

Fenaksite Image

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  Fenaksite

Comments: Tan to rose colored crystalline fenaksite with dark green-black crystalline pyroxene.
Location: Khibiny Massif, Kola Peninsula, Murmansk District, Russia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Fenaksite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.847:1:1.2111
Help on Cell Dimensions: Cell Dimensions: a = 6.98, b = 8.24, c = 9.98, Z = 1; alpha = 114.2°, beta = 80.22°, gamma = 115.6° V = 465.30 Den(Calc)= 2.88
Help on Crystal System: Crystal System: Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 3.03(1), 2.46(0.7), 3.55(0.7),
 

Physical Properties of Fenaksite

Help on Cleavage: Cleavage: {100} Good, {010} Good
Help on Color: Color: Brown, Light pink.
Help on Density: Density: 2.744
Help on Diaphaneity: Diaphaneity: Transparent to Translucent
Help on Habit: Habit: Granular - Generally occurs as anhedral to subhedral crystals in matrix.
Help on Hardness: Hardness: 5-5.5 - Apatite-Knife Blade
Help on Luster: Luster: Pearly
Help on Streak: Streak: white
 

Optical Properties of Fenaksite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.028 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.061 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1958,KPDmeas= 0.2026,KC= 0.2085
Ncalc = 1.57 - 1.59
Help on Optical Data: Optical Data: Biaxial (+), a=1.541, b=1.56, g=1.567, bire=0.0260, 2V(Calc)=60, 2V(Meas)=84.
 

Calculated Properties of Fenaksite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.70 gm/cc
note: Specific Gravity of Fenaksite =2.74 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.01
Boson Index = 0.99
Help on Photoelectric: Photoelectric: PEFenaksite = 6.44 barns/electron
U=PEFenaksite x relectron= 17.41 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 124.09 (Gamma Ray American Petroleum Institute Units)
Concentration of Fenaksite per GRapi unit = 0.81 (%)

Estimated Radioactivity from Fenaksite - barely detectable

 

Fenaksite Classification

Help on  Dana Class: Dana Class: 70.01.01.02 (70)Inosilicate Column or Tube Structures
  (70.01)with columnar silicate units
  (70.01.01)Litidionite group
 
70.01.01.01 Litidionite KNaCuSi4O10 P1 1
 
70.01.01.02 Fenaksite (K,Na,Ca)4(Fe,Fe,Mn)2Si8O20(OH,F) P1 1
 
70.01.01.03 Manaksite KNaMnSi4O10 P1 1
 
70.01.01.04 Agrellite NaCa2Si4O10F P1 1
Help on  Strunz Class: Strunz Class: 09.DG.70 09 - SILICATES (Germanates)
  09.D - Inosilicates* Structural terminology according to Liebau (1985)
  09.DG -Inosilicates with 3-periodic single and multiple chains
 
09.DG.70 Fenaksite (K,Na,Ca)4(Fe,Fe,Mn)2Si8O20(OH,F) P1 1
 
09.DG.70 Manaksite KNaMnSi4O10 P1 1
 

Other Fenaksite Information

Help on References: References: NAME( AntBidBlaNic2) PHYS. PROP.(AntBidBlaNic2) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
Help on See Also: See Also: Links to other databases for Fenaksite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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Print or Cut-and-Paste your Fenaksite Specimen Label here :

Fenaksite

(K,Na,Ca)4(Fe++,Fe+++,Mn)2Si8O20(OH,F)
Dana No: 70.01.01.02 Strunz No: 09.DG.70
Locality:

 

Notes:

 

 
   
 


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