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Jahnsite-(CaFeMg)

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About Jahnsite-(CaFeMg)Hide

Richard H. Jahns
Formula:
CaFe2+Mg2Fe3+2(PO4)4(OH)2·8H2O
Colour:
Brownish orange
Lustre:
Vitreous
Hardness:
4
Specific Gravity:
2.76
Crystal System:
Monoclinic
Name:
The root name is in honor of Richard Henry Jahns (March 10, 1915 Los Angeles, California, USA - December 31, 1983 Palo Alto, California, USA), mineralogist and pegmatite expert, Stanford University, Palo Alto, California, USA. The suffix indicates metal site occupancies.
Chemically similar to segelerite and also somewhat to wicksite.


Classification of Jahnsite-(CaFeMg)Hide

Approved
Approval Year:
2013
First Published:
2016

Physical Properties of Jahnsite-(CaFeMg)Hide

Vitreous
Transparency:
Transparent
Colour:
Brownish orange
Streak:
White
Hardness:
Comment:
ca. 4
Tenacity:
Brittle
Cleavage:
Distinct/Good
{001}
Fracture:
Splintery
Density:
2.76(4) g/cm3 (Measured)    2.772 g/cm3 (Calculated)

Optical Data of Jahnsite-(CaFeMg)Hide

Type:
Biaxial (-)
RI values:
nα = 1.629(4) nβ = 1.658(4) nγ = 1.677(4)
2V:
Calculated: 76.8°
Max Birefringence:
δ = 0.048
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate

Chemical Properties of Jahnsite-(CaFeMg)Hide

Formula:
CaFe2+Mg2Fe3+2(PO4)4(OH)2·8H2O
IMA Formula:
CaFe2+Mg2Fe3+2(PO4)4(OH)2 · 8H2O

Crystallography of Jahnsite-(CaFeMg)Hide

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P2/b
Setting:
P2/a
Cell Parameters:
a = 14.975(5) Å, b = 7.1645(14) Å, c = 9.928(2) Å
β = 110.65(3)°
Ratio:
a:b:c = 2.09 : 1 : 1.386
Unit Cell V:
996.72 ų (Calculated from Unit Cell)
Comment:
P2/a

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
9.339(100)
4.923(20)
3.562(20)
3.518(20)
3.453(20)
2.965(20)
2.839(35)
2.592(20)
Comments:
From Type Description.

Type Occurrence of Jahnsite-(CaFeMg)Hide

General Appearance of Type Material:
Prisms, up to 0.2 mm
Place of Conservation of Type Material:
Type material is deposited in the collections of the South Australian Museum, Adelaide, South Australia, Australia, registration number G34045
Geological Setting of Type Material:
Low-temperature secondary phase
Reference:
Elliott, P. (2016) Jahnsite-(CaFeMg), a new mineral from Tom’s quarry, South Australia: description and crystal structure. European Journal of Mineralogy: 28: 991-996.

Synonyms of Jahnsite-(CaFeMg)Hide

Relationship of Jahnsite-(CaFeMg) to other SpeciesHide

Other Members of this group:
Jahnsite-(CaFeFe){Ca}{Fe2+}{Fe2+2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon.
Jahnsite-(CaMnFe){Ca}{Mn2+}{Fe2+2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
Jahnsite-(CaMnMg){Ca}{Mn2+}{(Mg,Fe2+)2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
Jahnsite-(CaMnMn){Ca}{Mn2+}{Mn2+2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
Jahnsite-(MnMnFe2+)MnMn2+Fe2+2Fe3+2(PO4)4(OH)2·8H2O
Jahnsite-(MnMnMg)Mn2+Mn2+Mg2Fe3+2(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
Jahnsite-(MnMnMn){Mn2+}{Mn2+}{Mn2+2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon.
Jahnsite-(MnMnZn)Mn2+Mn2+Zn2Fe3+2(PO4)4(OH)2·8H2OMon. 2/m : P2/b
Jahnsite-(NaFeMg)NaFe3+Mg2Fe3+2(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b
Jahnsite-(NaMnMg){(Na,Ca)}{(Mn2+,Fe3+)}{(Mg,Fe3+)2}{Fe3+2}(PO4)4(OH)2 · 8H2OMon. 2/m : P2/b

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Jahnsite-(CaFeMg)Hide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Elliott, P. (2014) Jahnsite- (CaFeMg), IMA 2013-111. CNMNC Newsletter No. 19, February 2014, page 168; Mineralogical Magazine: 78: 165-170.
Elliott, P. (2016) Jahnsite-(CaFeMg), a new mineral from Tom’s quarry, South Australia: description and crystal structure. European Journal of Mineralogy: 28: 991-996.

Internet Links for Jahnsite-(CaFeMg)Hide

Localities for Jahnsite-(CaFeMg)Hide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Australia (TL)
 
  • South Australia
    • Mt Lofty Ranges
      • North Mt Lofty Ranges
        • Kapunda
Elliott, P. (2014) Jahnsite- (CaFeMg), IMA 2013-111. CNMNC Newsletter No. 19, February 2014, page 168; Mineralogical Magazine, 78, 165-170; Elliott, P. (2016): Jahnsite-(CaFeMg), a new mineral from Tom’s quarry, South Australia: description and crystal structure. European Journal of Mineralogy: 28:, 991-996.
Mineral and/or Locality  
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