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Jahnsite-(CaMgMg) Mineral Data
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General Jahnsite-(CaMgMg) Information
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 Chemical Formula: |
CaMgMg2Fe+++2(PO4)4(OH)2•8H2O |
| Composition: |
Molecular Weight = 782.71 gm |
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Calcium 5.12 % Ca 7.16 % CaO |
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Magnesium 9.32 % Mg 15.45 % MgO |
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Iron 14.27 % Fe 20.40 % Fe2O3 |
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Phosphorus 15.83 % P 36.27 % P2O5 |
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Hydrogen 2.32 % H 20.71 % H2O |
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Oxygen 53.15 % O |
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______ ______ |
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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
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| Crystal System: |
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 2/a |
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Physical Properties of Jahnsite-(CaMgMg)
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| 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 |
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Optical Properties of Jahnsite-(CaMgMg)
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| Optical Data: |
Biaxial (-) |
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NCalc= 1.64 - from Gladstone-Dale relationship (KC = 0.247) where Ncalc=Dmeas*KC+1 |
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Calculated Properties of Jahnsite-(CaMgMg)
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| Electron Density: |
Bulk Density (Electron Density)=2.60 gm/cc
note: Specific Gravity of Jahnsite-(CaMgMg) =2.58 gm/cc.
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| Fermion Index: |
Fermion Index = 0.01
Boson Index = 0.99 |
| Photoelectric: |
PEJahnsite-(CaMgMg) = 5.77 barns/electron
U=PEJahnsite-(CaMgMg) x rElectron Density= 14.99 barns/cc.
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| Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Jahnsite-(CaMgMg) is Not Radioactive |
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Jahnsite-(CaMgMg) Classification
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| Dana Class: |
42.11.03.07 (42)Hydrated Phosphates, etc., Containing Hydroxyl or Halogen |
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(42.11)where (AB)4 (XO4)3 Zq � x(H2O) |
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(42.11.03)Whiteite Group |
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42.11.03.01 Whiteite-(CaFeMg) Ca(Fe,Mn)Mg2Al2(PO4)4(OH)2•8(H2O) P 21/a 2/m |
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42.11.03.02 Whiteite-(MnFeMg) (Mn,Ca)(Fe,Mn)Mg2Al2(PO4)4(OH)2•8(H2O) P 2/a 2/m |
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42.11.03.03 Whiteite-(CaMnMg) CaMnMg2Al2(PO4)4(OH)2•8(H2O) P 2/a 2/m |
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42.11.03.04 Rittmannite MnMnFeAl2(OH)2(PO4)4•8(H2O) P 2/a 2/m |
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42.11.03.05 Jahnsite-(CaFeFe)! (Ca,Mn)(Fe,Mn)Fe2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m |
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42.11.03.06 Jahnsite-(NaFeMg)! NaFeMg2Fe2(PO4)4(OH)2•8H2O P 2/a 2/m |
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42.11.03.07 Jahnsite-(CaMgMg)! CaMgMg2Fe2(PO4)4(OH)2•8H2O P 2/a 2/m |
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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 |
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08.D - Phosphates, etc |
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08.DH -With large and medium-sized cations, (OH, etc.):RO4 < 1:1 |
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08.DH.15 Keckite Ca(Mn,Zn)2Fe3(PO4)4(OH)3•2(H2O) P 21/a 2/m |
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08.DH.15 Jahnsite-(CaMnFe) CaMnFe2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m |
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08.DH.15 Jahnsite-(CaMnMg) CaMnMg2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m |
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08.DH.15 Jahnsite-(CaMnMn) CaMnMn2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m |
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08.DH.15 Jahnsite-(MnMnMn)* MnMnMn2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m |
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08.DH.15 Kaluginite* (Mn,Ca)MgFe(PO4)2(OH)•4(H2O) C cca 2/m 2/m 2/m |
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08.DH.15 Rittmannite MnMnFeAl2(OH)2(PO4)4•8(H2O) P 2/a 2/m |
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08.DH.15 Whiteite-(MnFeMg) (Mn,Ca)(Fe,Mn)Mg2Al2(PO4)4(OH)2•8(H2O) P 2/a 2/m |
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08.DH.15 Whiteite-(CaFeMg) Ca(Fe,Mn)Mg2Al2(PO4)4(OH)2•8(H2O) P 21/a 2/m |
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08.DH.15 Whiteite-(CaMnMg) CaMnMg2Al2(PO4)4(OH)2•8(H2O) P 2/a 2/m |
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08.DH.15 Jahnsite-(CaFeFe)! (Ca,Mn)(Fe,Mn)Fe2Fe2(PO4)4(OH)2•8(H2O) P 2/a 2/m |
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08.DH.15 Jahnsite-(NaFeMg)! NaFeMg2Fe2(PO4)4(OH)2•8H2O P 2/a 2/m |
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08.DH.15 Jahnsite-(CaMgMg)! CaMgMg2Fe2(PO4)4(OH)2•8H2O P 2/a 2/m |
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08.DH.15 Jahnsite-(NaMnMg)! NaMnMg2Fe2(PO4)4(OH)2•8H2O P 2/a 2/m |
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Other Jahnsite-(CaMgMg) Information
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| 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 :
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Jahnsite-(CaMgMg)
CaMgMg2Fe+++2(PO4)4(OH)2•8H2O
Dana No: 42.11.03.07 Strunz No: 08.DH.15
Locality:
Notes:
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