Mineralogy Database

Fayalite Mineral Data

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General Fayalite Information

Help on Chemical  Formula: Chemical Formula: Fe++2SiO4
Help on Composition: Composition: Molecular Weight = 203.78 gm
   Iron     54.81 %  Fe   70.51 % FeO
   Silicon  13.78 %  Si   29.49 % SiO2
   Oxygen   31.41 %  O
           ______        ______ 
           100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Fe2+2(SiO4)
Help on Environment: Environment: Ultra mafic silica-poor igneous rocks.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1840
Help on Locality: Locality: Fayal Island, Azores Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for the locality
Help on Name Pronunciation: Name Pronunciation: Fayalite Say FAYALITE
Help on Synonym: Synonym: Hortonolite - Mn,Mg
  ICSD 26375
  Knebelite(Mn)
  PDF 31-633
 

Fayalite Image

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  Fayalite

Comments: Flattened crystals of fayalite on cristobalite.
Location: Coso Hot Springs, Inyo County, California. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Fayalite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.4666:1:0.5862
Help on Cell Dimensions: Cell Dimensions: a = 4.76, b = 10.2, c = 5.98, Z = 4; V = 290.34 Den(Calc)= 4.66
Help on Crystal System: Crystal System: Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Pbnm
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.831(1), 2.501(0.7), 2.566(0.5),
 

Physical Properties of Fayalite

Help on Cleavage: Cleavage: {010} Indistinct
Help on Color: Color: Brown, Black, Black.
Help on Density: Density: 4.39
Help on Diaphaneity: Diaphaneity: Transparent to Translucent
Help on Fracture: Fracture: Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Help on Habit: Habit: Granular - Generally occurs as anhedral to subhedral crystals in matrix.
Help on Habit: Habit: Massive - Granular - Common texture observed in granite and other igneous rock.
Help on Hardness: Hardness: 6.5 - Pyrite
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: white
 

Optical Properties of Fayalite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.055 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.11 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1726,KPDmeas= 0.1833,KC= 0.1939
Ncalc = 1.85 - 1.9
Help on Optical Data: Optical Data: Biaxial (-), a=1.731-1.824, b=1.76-1.864, g=1.773-1.875, bire=0.0420-0.0510, 2V(Calc)=54-66, 2V(Meas)=74-47. Dispersion weak, r > v.
Help on Pleochroism (x): Pleochroism (x): greenish yellow, pale yellow, or pale amber.
Help on Pleochroism (y): Pleochroism (y): orange yellow, orange yellow, or orange yellow.
Help on Pleochroism (z): Pleochroism (z): greenish yellow, pale yellow, or pale amber.
 

Calculated Properties of Fayalite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=4.22 gm/cc
note: Specific Gravity of Fayalite =4.39 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.01
Boson Index = 0.99
Help on Photoelectric: Photoelectric: PEFayalite = 17.09 barns/electron
U=PEFayalite x rElectron Density= 72.16 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Fayalite is Not Radioactive
 

Fayalite Classification

Help on  Dana Class: Dana Class: 51.03.01.01 (51)Nesosilicate Insular SiO4 Groups Only
  (51.03)with all cations in octahedral [6] coordination
  (51.03.01)Olivine group
 
51.03.01.00 Olivine* (Mg,Fe)2SiO4 Pbnm 2/m 2/m 2/m
 
51.03.01.01 Fayalite Fe2SiO4 Pbnm 2/m 2/m 2/m
 
51.03.01.02 Forsterite Mg2SiO4 Pbnm 2/m 2/m 2/m
 
51.03.01.03 Liebenbergite (Ni,Mg)2SiO4 Pbnm 2/m 2/m 2/m
 
51.03.01.04 Tephroite Mn2SiO4 P nma 2/m 2/m 2/m
 
51.03.01.05 Laihunite FeFe2(SiO4)2 P 21/b 2/m
Help on  Strunz Class: Strunz Class: 09.AC.05 09 - SILICATES (Germanates)
  09.A - Nesosilicates
  09.AC -Nesosilicates without additional anions;
 
09.AC.05 Forsterite Mg2SiO4 Pbnm 2/m 2/m 2/m
 
09.AC.05 Glaucochroite CaMnSiO4 Pbnm 2/m 2/m 2/m
 
09.AC.05 Fayalite Fe2SiO4 Pbnm 2/m 2/m 2/m
 
09.AC.05 Olivine* (Mg,Fe)2SiO4 Pbnm 2/m 2/m 2/m
 
09.AC.05 Kirschsteinite CaFeSiO4 Pbmn 2/m 2/m 2/m
 
09.AC.05 Laihunite FeFe2(SiO4)2 P 21/b 2/m
 
09.AC.05 Liebenbergite (Ni,Mg)2SiO4 Pbnm 2/m 2/m 2/m
 
09.AC.05 Tephroite Mn2SiO4 P nma 2/m 2/m 2/m
 

Other Fayalite Information

Help on References: References: NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)
Help on See Also: See Also: Links to other databases for Fayalite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - CalTech Mineral Spectroscopy
5 - EUROmin Project
6 - Ecole des Mines de Paris
7 - Franklin Minerals(Dunn)
8 - GeoScienceWorld
9 - Google Images
10 - Google Scholar
11 - Handbook of Mineralogy (MinSocAm)
12 - Handbook of Mineralogy (UofA)
13 - MinDAT
14 - Mineralienatlas (Deutsch)
15 - Online Mineral Museum
16 - QUT Mineral Atlas
17 - Ruff.Info
18 - UCLA - Petrography Thin-Sections
19 - University of Colorado - Mineral Structure Data
20 - University of Texas at Austin
21 - WWW-MINCRYST

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Fayalite

Fe++2SiO4
Dana No: 51.03.01.01 Strunz No: 09.AC.05
Locality:

 

Notes:

 

 
   
 


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