Jahnsite-(CaMgMg) Mineral Data

General Jahnsite-(CaMgMg) Information

Chemical Formula:

CaMgMg2Fe+++2(PO4)4(OH)2•8H2O

Composition:

Molecular Weight = 782.71 gm

Calcium 5.12 % Ca 7.16 % CaO

Magnesium 9.32 % Mg 15.45 % MgO

Iron 14.27 % Fe 20.40 % Fe₂O₃

Phosphorus 15.83 % P 36.27 % P₂O₅

Hydrogen 2.32 % H 20.71 % H₂O

Oxygen 53.15 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

CaMg₃Fe³⁺₂(PO₄)₄(OH)₂•8(H₂O)

Environment:

Zoned tip on Jahnsite-(NaFeMg). Whiteite-jahnsite group.

IMA Status:

Not Submitted IMA (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-(CaMgMg)

Synonym:

IMA2007-016

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Jahnsite-(CaMgMg) Crystallography

Crystal System:

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

Physical Properties of Jahnsite-(CaMgMg)

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-(CaMgMg)

Optical Data:

Biaxial (-)

NCalc= 1.64 - from Gladstone-Dale relationship (KC = 0.247) where Ncalc=Dmeas*KC+1

Calculated Properties of Jahnsite-(CaMgMg)

Electron Density:

Bulk Density (Electron Density)=2.60 gm/cc
note: Specific Gravity of Jahnsite-(CaMgMg) =2.58 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_{Jahnsite-(CaMgMg)}= 5.77 barns/electron
U=PE_{Jahnsite-(CaMgMg)} x rElectron Density= 14.99 barns/cc.

Radioactivity:

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

Jahnsite-(CaMgMg) Classification

Dana Class:

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

(42.11)where (AB)4 (XO4)3 Zq · 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-(CaMgMg) Information

References:

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

See Also:

Links to other databases for Jahnsite-(CaMgMg) :
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-(CaMgMg) Specimen Label here :

Jahnsite-(CaMgMg)

CaMgMg2Fe+++2(PO4)4(OH)2•8H2O
Dana No: 42.11.03.07 Strunz No: 08.DH.15
Locality:

Notes: