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Jahnsite-(NaFeMg)
A valid IMA mineral species
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About Jahnsite-(NaFeMg)
Richard H. Jahns
Formula:
{Na}{Fe3+}{Mg2}{Fe3+2}(PO4)4(OH)2 · 8H2O
Colour:
yellow, orange-red
Lustre:
Vitreous
Hardness:
4
Specific Gravity:
2.58
Crystal System:
Monoclinic
Member of:
Name:
For the mineral jahnsite and its sodium, iron and magnesium content.
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 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.
Unique Identifiers
Mindat ID:
31994
Long-form identifier:
mindat:1:1:31994:0
Similar Names
| Jahnsite | A synonym of Jahnsite Subgroup | |
| Jahnsite-(CaFeFe) | Valid as an unnamed mineral | {Ca}{Fe2+}{Fe22+}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(CaFeMg) | A valid IMA mineral species | {Ca}{Fe2+}{Mg2}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(CaMgMg) | Valid as an unnamed mineral | {Ca}{Mg}{Mg2}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(CaMnFe) | A valid IMA mineral species | {Ca}{Mn2+}{Fe22+}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(CaMnMg) | A valid IMA mineral species | {Ca}{Mn2+}{(Mg,Fe2+)2}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(CaMnMn) | A valid IMA mineral species | {Ca}{Mn2+}{Mn22+}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(CaMnZn) | A valid IMA mineral species | {Ca}{Mn2+}{Zn2}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(MnMnFe) | A valid IMA mineral species | {Mn2+}{Mn2+}{Fe22+}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(MnMnMg) | A valid IMA mineral species | {Mn2+}{Mn2+}{Mg2}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(MnMnMn) | A valid IMA mineral species | {Mn2+}{Mn2+}{Mn22+}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(MnMnZn) | A valid IMA mineral species | {Mn2+}{Mn2+}{Zn2}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(NaMnMg) | A valid IMA mineral species | {(Na,Ca)}{(Mn2+,Fe3+)}{(Mg,Fe3+)2}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Jahnsite-(NaMnMn) | A valid IMA mineral species | {Na}{Mn2+}{(Mn2+,Fe3+)2}{Fe23+}(PO4)4(OH)2 · 8H2O |
| Janosite | A synonym of Copiapite | |
| Jonesite | A valid IMA mineral species | Ba4(K,Na)2Ti4Al2(Si3O9)2(SiO4)4O2 · 6H2O |
Classification of Jahnsite-(NaFeMg)
The jahnsite structure archetype
The structure archetype of jahnsite group minerals, which includes the jahnsite and whiteite subgroups.
IMA Classification of Jahnsite-(NaFeMg)
Approved
IMA Formula:
NaFe3+Mg2Fe3+2(PO4)4(OH)2·8H2O
Approval year:
2007
8.DH.15
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
H : With large and medium-sized cations, (OH, etc.):RO4 < 1:1
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
H : With large and medium-sized cations, (OH, etc.):RO4 < 1:1
42.11.2.6
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
11 : (AB)3(XO4)2Zq·xH2O
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
11 : (AB)3(XO4)2Zq·xH2O
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Jah-NaFeMg | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Jhn | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Jahnsite-(NaFeMg)
Vitreous
Transparency:
Transparent
Colour:
Yellow, orange-red
Comment:
orange-red bands near their terminations
Streak:
White
Hardness:
4 on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
{001}
{001}
Fracture:
Splintery
Density:
2.58(2) g/cm3 (Measured) 2.608 g/cm3 (Calculated)
Optical Data of Jahnsite-(NaFeMg)
Type:
Biaxial (-)
RI values:
nα = 1.632(1) nβ = 1.669(1) nγ = 1.671(1)
2V:
Measured: 25° (5), Calculated: 26°
Max. Birefringence:
δ = 0.039
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Moderate
Dispersion:
r > v, very strong
Pleochroism:
Visible
Comments:
X = colorless, Y and Z = beige; Y = Z > X.
Chemistry of Jahnsite-(NaFeMg)
Mindat Formula:
{Na}{Fe3+}{Mg2}{Fe3+2}(PO4)4(OH)2 · 8H2O
Element Weights:
Crystallography of Jahnsite-(NaFeMg)
Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P2/b
Setting:
P2/a
Cell Parameters:
a = 15.0811(16) Å, b = 7.1403(8) Å, c = 9.8299(11) Å
β = 110.445(1)°
β = 110.445(1)°
Ratio:
a:b:c = 2.112 : 1 : 1.377
Unit Cell V:
991.84 ų (Calculated from Unit Cell)
Z:
2
Twinning:
simple contact and polysynthetic by reflection on {001}. The twinning combines with the prism forms {011} and {001} and the terminal form {100} to yield six-sided pseudo-orthorhombic prisms with shallow wedge-like terminations
Crystal Structure
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0004587 | Jahnsite-(NaFeMg) | Kampf A R, Steele I M, Loomis T A (2008) Jahnsite-(NaFeMg), a new mineral from the Tip Top mine, Custer County, South Dakota: Description and crystal structure American Mineralogist 93 940-945 |  | 2008 | Tip Top mine, Custer County, South Dakota | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 9.218 Å | (100) |
| 4.884 Å | (25) |
| 3.537 Å | (25) |
| 2.973 Å | (25) |
| 2.854 Å | (20) |
| 2.819 Å | (70) |
| 2.593 Å | (25) |
| 1.933 Å | (20) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Type Occurrence of Jahnsite-(NaFeMg)
General Appearance of Type Material:
prismatic along [100]
Place of Conservation of Type Material:
mineral collection of the Natural History Museum of Los Angeles County (catalog numbers 58590, 58591, and 58592).
Geological Setting of Type Material:
highly altered and oxidized triphylite pod from pegmatite
Associated Minerals at Type Locality:
Tip Top Mine, Fourmile, Custer Mining District, Custer County, South Dakota, USA