Jahnsite-(NaFeMg) Mineral Data

General Jahnsite-(NaFeMg) Information

Chemical Formula:

NaFe+++Mg2Fe+++2(PO4)4(OH)2•8H2O

Composition:

Molecular Weight = 780.46 gm

Sodium 2.12 % Na 2.86 % Na₂O

Calcium 0.26 % Ca 0.36 % CaO

Magnesium 6.26 % Mg 10.38 % MgO

Manganese 0.28 % Mn 0.36 % MnO

Iron 19.46 % Fe 27.83 % Fe₂O₃

Phosphorus 15.87 % P 36.37 % P₂O₅

Hydrogen 2.44 % H 21.84 % H₂O

Oxygen 53.30 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Na_0.72Ca_0.05Mn²⁺_0.04Fe³⁺_0.72Mg_0.01Mg₂Fe³⁺₂4(P)4(O_3.77)4(OH)_0.23(OH)₂ï¿½8(H₂O)

Environment:

Found in a single football-sized rock, consisting mainly of heterosite and presumed to be a fragment of highly altered and oxidized triphylite. Whiteite-jahnsite group.

IMA Status:

Approved IMA 2007 (Dana # Added)

Locality:

Tip Top mine, Custer County, South Dakota, USA. Link to MinDat.org Location Data.

Name Origin:

Named for Richard H. Jahns (1915-1983), mineralogist and pegmatite expert, Stanford University, Palo Alto, California, USA.

Name Pronunciation:

Jahnsite-(NaFeMg)

Synonym:

IMA2007-016

Jahnsite-(NaFeMg) Crystallography

Axial Ratios:

a:b:c =2.1121:1:1.3766

Cell Dimensions:

a = 15.0811, b = 7.1403, c = 9.8299, Z = 2; beta = 110.445° V = 991.84 Den(Calc)= 2.61

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 2/a

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

By Intensity(I/I_o): 9.218(1), 2.819(0.7), 2.593(0.25),2.973(0.25), 3.537(0.25), 4.884(0.25), 1.933(0.2), 2.854(0.2),

Physical Properties of Jahnsite-(NaFeMg)

Color:

Yellow.

Density:

2.58

Diaphaneity:

Transparent

Fracture:

Brittle - Splintery - Brittle fracture leaving splintery fragments.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Habit:

Striated - Parallel lines on crystal surface or cleavage face.

Hardness:

4 - Fluorite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Jahnsite-(NaFeMg)

Gladstone-Dale:

CI meas= 0.005 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.017 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2519,KPDmeas= 0.2548,KC= 0.2561
Ncalc = 1.66 - 1.67

Optical Data:

Biaxial (-), a=1.632, b=1.669, g=1.671, bire=0.0390, 2V(Calc)=24, 2V(Meas)=25. Dispersion very strong, r > v.

Calculated Properties of Jahnsite-(NaFeMg)

Electron Density:

Bulk Density (Electron Density)=2.59 gm/cc
note: Specific Gravity of Jahnsite-(NaFeMg) =2.58 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_{Jahnsite-(NaFeMg)}= 6.74 barns/electron
U=PE_{Jahnsite-(NaFeMg)} x rElectron Density= 17.46 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Jahnsite-(NaFeMg) is Not Radioactive

Jahnsite-(NaFeMg) Classification

Dana Class:

42.11.03.06 (42)Hydrated Phosphates, etc., Containing Hydroxyl or Halogen

(42.11)where (AB)4 (XO4)3 Zq ï¿½ x(H2O)

(42.11.03)Whiteite Group

42.11.03.01 Whiteite-(CaFeMg) Ca(Fe,Mn)Mg2Al2(PO4)4(OH)2•8(H2O) P 2₁/a 2/m

42.11.03.02 Whiteite-(MnFeMg) (Mn,Ca)(Fe,Mn)Mg2Al2(PO4)4(OH)2•8(H2O) P 2/a 2/m

42.11.03.03 Whiteite-(CaMnMg) CaMnMg2Al2(PO4)4(OH)2•8(H2O) P 2/a 2/m

42.11.03.04 Rittmannite MnMnFeAl2(OH)2(PO4)4•8(H2O) P 2/a 2/m

42.11.03.05 Jahnsite-(CaFeFe)! (Ca,Mn)(Fe,Mn)Fe2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m

42.11.03.06 Jahnsite-(NaFeMg)! NaFeMg2Fe2(PO4)4(OH)2•8H2O P 2/a 2/m

42.11.03.07 Jahnsite-(CaMgMg)! CaMgMg2Fe2(PO4)4(OH)2•8H2O P 2/a 2/m

42.11.03.08 Jahnsite-(NaMnMg)! NaMnMg2Fe2(PO4)4(OH)2•8H2O P 2/a 2/m

Strunz Class:

08.DH.15 08 - PHOSPHATES, ARSENATES, VANADATES

08.D - Phosphates, etc

08.DH -With large and medium-sized cations, (OH, etc.):RO4 < 1:1

08.DH.15 Keckite Ca(Mn,Zn)2Fe3(PO4)4(OH)3•2(H2O) P 2₁/a 2/m

08.DH.15 Jahnsite-(CaMnFe) CaMnFe2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m

08.DH.15 Jahnsite-(CaMnMg) CaMnMg2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m

08.DH.15 Jahnsite-(CaMnMn) CaMnMn2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m

08.DH.15 Jahnsite-(MnMnMn)* MnMnMn2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m

08.DH.15 Kaluginite* (Mn,Ca)MgFe(PO4)2(OH)•4(H2O) C cca 2/m 2/m 2/m

08.DH.15 Rittmannite MnMnFeAl2(OH)2(PO4)4•8(H2O) P 2/a 2/m

08.DH.15 Whiteite-(MnFeMg) (Mn,Ca)(Fe,Mn)Mg2Al2(PO4)4(OH)2•8(H2O) P 2/a 2/m

08.DH.15 Whiteite-(CaFeMg) Ca(Fe,Mn)Mg2Al2(PO4)4(OH)2•8(H2O) P 2₁/a 2/m

08.DH.15 Whiteite-(CaMnMg) CaMnMg2Al2(PO4)4(OH)2•8(H2O) P 2/a 2/m

08.DH.15 Jahnsite-(CaFeFe)! (Ca,Mn)(Fe,Mn)Fe2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m

08.DH.15 Jahnsite-(NaFeMg)! NaFeMg2Fe2(PO4)4(OH)2•8H2O P 2/a 2/m

08.DH.15 Jahnsite-(CaMgMg)! CaMgMg2Fe2(PO4)4(OH)2•8H2O P 2/a 2/m

08.DH.15 Jahnsite-(NaMnMg)! NaMnMg2Fe2(PO4)4(OH)2•8H2O P 2/a 2/m

Other Jahnsite-(NaFeMg) Information

References:

NAME( AmMin, v93:940) PHYS. PROP.(AmMin, v93:940) OPTIC PROP.(AmMin, v93:940)

See Also:

Links to other databases for Jahnsite-(NaFeMg) :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Print or Cut-and-Paste your Jahnsite-(NaFeMg) Specimen Label here :

Jahnsite-(NaFeMg)

NaFe+++Mg2Fe+++2(PO4)4(OH)2•8H2O
Dana No: 42.11.03.06 Strunz No: 08.DH.15
Locality:

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