Fairfieldite Mineral Data

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General Fairfieldite Information

Chemical Formula:

Ca2(Mn,Fe++)(PO4)2•2(H2O)

Composition:

Molecular Weight = 361.29 gm

Calcium 22.19 % Ca 31.04 % CaO

Manganese 11.40 % Mn 14.73 % MnO

Iron 3.86 % Fe 4.97 % FeO

Phosphorus 17.15 % P 39.29 % P₂O₅

Hydrogen 1.12 % H 9.97 % H₂O

Oxygen 44.28 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₂Mn²⁺_0.75Fe²⁺_0.25(PO₄)₂•2(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1879

Locality:

Branchville, Redding, Fairfield County, Connecticut, USA Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Name Pronunciation:

Fairfieldite + Pronunciation

Synonym:

ICSD 16017

PDF 10-390

Fairfieldite Image

Images:

Fairfieldite

Comments: Transparent, cockscomb druse of fairfieldite crystals.
Location: Foote mine, Kings Mountain, Cleveland County, North Carolina, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Fairfieldite Crystallography

Axial Ratios:

a:b:c =0.8797:1:0.834

Cell Dimensions:

a = 5.78, b = 6.57, c = 5.48, Z = 1; alpha = 102.1°, beta = 108.7°, gamma = 90.09° V = 192.74 Den(Calc)= 3.11

Crystal System:

Triclinic - PinacoidalH-M Symbol ( 1) Space Group: P1

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 3.23(1), 6.4(0.9), 3.03(0.8),

Forms:

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Forms: ( 1 1 1) ( 1 1 0) ( 0 1 0) ( 0 0 1)

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Crystal Structure:

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Fanfani L , Nunzi A , Zanazzi P F , Acta Crystallographica, Section B , 26 (1970) p.640-645, The crystal structure of fairfieldite, Locality: Foote Mine, North Carolina, USA

Physical Properties of Fairfieldite

Cleavage:

{???} Perfect, {???} Distinct

Color:

Greenish white, White, Light yellow.

Density:

3.1

Diaphaneity:

Transparent

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Euhedral Crystals - Occurs as well-formed crystals showing good external form.

Habit:

Fibrous - Crystals made up of fibers.

Habit:

Foliated - Two dimensional platy forms.

Hardness:

3.5 - Copper Penny

Luminescence:

Non-fluorescent.

Luster:

Vitreous - Pearly

Streak:

white

Optical Properties of Fairfieldite

Gladstone-Dale:

CI meas= 0.003 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.009 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2075,KPDmeas= 0.2088,KC= 0.2093
Ncalc = 1.65

Optical Data:

Biaxial (+), a=1.636-1.64, b=1.644-1.65, g=1.654-1.66, bire=0.0180-0.0200, 2V(Calc)=86-88, 2V(Meas)=86. Dispersion relatively weak.

Calculated Properties of Fairfieldite

Electron Density:

Bulk Density (Electron Density)=3.08 gm/cc
note: Specific Gravity of Fairfieldite =3.10 gm/cc.

Fermion Index:

Fermion Index = 0.0013329887
Boson Index = 0.9986670113

Photoelectric:

PE_Fairfieldite= 7.55 barns/electron
U=PE_Fairfieldite x rElectron Density= 23.23 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Fairfieldite is Not Radioactive

Fairfieldite Classification

Dana Class:

40.02.02.01 (40)Hydrated Phosphates, etc

(40.02)where A++ (B++)2 (XO4) · x(H2O)

(40.02.02)Fairfieldite Subgroup (Triclinic: P-1¯)

40.02.02.01 Fairfieldite Ca2(Mn,Fe)(PO4)2•2(H2O) P1 1

40.02.02.02 Messelite Ca2(Fe,Mn)(PO4)2•2(H2O) P1 1

40.02.02.03 Collinsite Ca2(Mg,Fe)(PO4)2•2(H2O) P1 1

40.02.02.04 Cassidyite Ca2(Ni,Mg)(PO4)2•2(H2O) P1 1

40.02.02.05 Talmessite Ca2Mg(AsO4)2•2(H2O) P1 1

40.02.02.06 Gaitite Ca2Zn(AsO4)2•2(H2O) P1 1

40.02.02.07 Roselite-beta Ca2(Co,Mg)(AsO4)2•2(H2O) P 1 or P1 Tri

40.02.02.08 Parabrandtite Ca2Mn(AsO4)•2(H2O) P1,P 1 Tri

40.02.02.09 Hillite! Ca2(Zn,Mg)[PO4]2•2(H2O) P1 1

40.02.02.10 Nickeltalmessite! Ca2Ni(AsO4)2•2H2O P 1

Strunz Class:

08.CG.05 08 - PHOSPHATES, ARSENATES, VANADATES

08.C - Phosphates without Additional Anions, with H2O

08.CG -With large and medium-sized cations, RO4:H2O = 1:1

08.CG.05 Collinsite Ca2(Mg,Fe)(PO4)2•2(H2O) P1 1

08.CG.05 Gaitite Ca2Zn(AsO4)2•2(H2O) P1 1

08.CG.05 Cassidyite Ca2(Ni,Mg)(PO4)2•2(H2O) P1 1

08.CG.05 Fairfieldite Ca2(Mn,Fe)(PO4)2•2(H2O) P1 1

08.CG.05 Messelite Ca2(Fe,Mn)(PO4)2•2(H2O) P1 1

08.CG.05 Parabrandtite Ca2Mn(AsO4)•2(H2O) P1,P 1 Tri

08.CG.05 Uranophane-beta Ca[(UO2)SiO3(OH)]2•(H2O) P 2₁/a 2/m

08.CG.05 Talmessite Ca2Mg(AsO4)2•2(H2O) P1 1

08.CG.05 Hillite! Ca2(Zn,Mg)[PO4]2•2(H2O) P1 1

Other Fairfieldite Information

References:

PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Fairfieldite :
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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Ask about Fairfieldite here :
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Print or Cut-and-Paste your Fairfieldite Specimen Label here :

Fairfieldite

Ca2(Mn,Fe++)(PO4)2•2(H2O)
Dana No: 40.02.02.01 Strunz No: 08.CG.05
Locality:

Notes: