Irhtemite
A valid IMA mineral species
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About Irhtemite
Formula:
Ca4Mg(AsO4)2(HAsO4)2 · 4H2O
Colour:
Colorless, white, pale rose
Lustre:
Silky
Specific Gravity:
3.09
Crystal System:
Monoclinic
Name:
Named after the type locality, the Ightem Mine (Irhtem Mine).
This page provides mineralogical data about Irhtemite.
Unique Identifiers
Mindat ID:
2043
Long-form identifier:
mindat:1:1:2043:1
IMA Classification of Irhtemite
Approved
IMA Formula:
Ca4Mg(As5+O4)2(As5+O3OH)2·4H2O
Approval year:
1971
Classification of Irhtemite
8.CG.55
8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
G : With large and medium-sized cations, RO4:H2O = 1:1
8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
G : With large and medium-sized cations, RO4:H2O = 1:1
39.2.5.1
39 : HYDRATED ACID PHOSPHATES,ARSENATES AND VANADATES
2 : (AB)5[HXO4]2[XO4]2.xH2O
39 : HYDRATED ACID PHOSPHATES,ARSENATES AND VANADATES
2 : (AB)5[HXO4]2[XO4]2.xH2O
20.2.19
20 : Arsenates (also arsenates with phosphate, but without other anions)
2 : Arsenates of Be, Mg, Ca or Ba
20 : Arsenates (also arsenates with phosphate, but without other anions)
2 : Arsenates of Be, Mg, Ca or Ba
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Irh | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Irhtemite
Silky
Transparency:
Transparent
Colour:
Colorless, white, pale rose
Streak:
White
Density:
3.09 g/cm3 (Measured) 3,153 g/cm3 (Calculated)
Optical Data of Irhtemite
Type:
Biaxial (+)
RI values:
nα = 1.634 nγ = 1.642
Max. Birefringence:
δ = 0.008
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:
strong
Optical Extinction:
Extinction angle 25°.
Comments:
Elongation negative.
Chemistry of Irhtemite
Mindat Formula:
Ca4Mg(AsO4)2(HAsO4)2 · 4H2O
Element Weights:
Crystallography of Irhtemite
Crystal System:
Monoclinic
Cell Parameters:
a = 16.736(5) Å, b = 9.483(3) Å, c = 10.840(5) Å
β = 97.25°
β = 97.25°
Ratio:
a:b:c = 1.765 : 1 : 1.143
Unit Cell V:
1,706.63 ų (Calculated from Unit Cell)
Z:
4
Comment:
Point Group: n.d.; Space Group: n.d.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 9.42 Å | (30) |
| 6.85 Å | (30) |
| 5.08 Å | (40) |
| 3.68 Å | (40) |
| 3.24 Å | (90) |
| 2.97 Å | (100) |
| 2.82 Å | (90) |
Comments:
Ightem Mine, Morocco. Data from the type description.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] |
Type Occurrence of Irhtemite
General Appearance of Type Material:
Spherulites 0.5-1 mm in diameter.
Place of Conservation of Type Material:
National School of Mines, Paris, France.
Geological Setting of Type Material:
Dehydration product of picropharmacolite in hydrothermal veins.
Associated Minerals at Type Locality:
Synonyms of Irhtemite
Other Language Names for Irhtemite
Common Associates
Associations Based on Photo Data:
| 7 photos of Irhtemite associated with Calcite | CaCO3 |
| 7 photos of Irhtemite associated with Vladimirite | Ca4(AsO4)2(AsO3OH) · 4H2O |
Related Minerals - Strunz-mindat Grouping
| 8.CG. | Fluckite | CaMn2+(AsO3OH)2 · 2H2O |
| 8.CG. | Dondoellite | Ca2Fe(PO4)2 · 2H2O |
| 8.CG. | 'Ca-Huréaulite' | CaMn5(PO4)4 · 4H2O |
| 8.CG. | Alumolukrahnite | Ca[CuAl](AsO4)2(H2O,OH)2 |
| 8.CG.05 | Parabrandtite | Ca2Mn2+(AsO4)2 · 2H2O |
| 8.CG.05 | Talmessite | Ca2Mg(AsO4)2 · 2H2O |
| 8.CG.05 | Collinsite | Ca2Mg(PO4)2 · 2H2O |
| 8.CG.05 | Messelite | Ca2Fe2+(PO4)2 · 2H2O |
| 8.CG.05 | Gaitite | Ca2Zn(AsO4)2 · 2H2O |
| 8.CG.05 | Anorthoroselite | Ca2Co(AsO4)2 · 2H2O |
| 8.CG.05 | Cassidyite | Ca2Ni(PO4)2 · 2H2O |
| 8.CG.05 | Fairfieldite | Ca2Mn2+(PO4)2 · 2H2O |
| 8.CG.05 | Hillite | Ca2Zn(PO4)2 · 2H2O |
| 8.CG.05 | 'Unnamed (Fe2+-analogue of Parabrandtite)' | Ca2Fe2+(AsO4)2 · 2H2O |
| 8.CG.10 | Zincroselite | Ca2Zn(AsO4)2 · 2H2O |
| 8.CG.10 | Roselite | Ca2Co(AsO4)2 · 2H2O |
| 8.CG.10 | Rruffite | Ca2Cu(AsO4)2 · 2H2O |
| 8.CG.10 | Wendwilsonite | Ca2Mg(AsO4)2 · 2H2O |
| 8.CG.10 | Brandtite | Ca2Mn2+(AsO4)2 · 2H2O |
| 8.CG.10 | 'Unnamed (Fe2+-analogue of Brandtite)' | Ca2Fe2+(AsO4)2 · 2H2O |
| 8.CG.15 | Mawbyite | PbFe3+2(AsO4)2(OH)2 |
| 8.CG.15 | Thometzekite | PbCu2+2(AsO4)2 · 2H2O |
| 8.CG.15 | Yancowinnaite | PbCuAl(AsO4)2OH · H2O |
| 8.CG.15 | Schneebergite | BiCo2(AsO4)2(OH) · H2O |
| 8.CG.15 | Cabalzarite | CaMg2(AsO4)2 · 2H2O |
| 8.CG.15 | Nickelschneebergite | BiNi2(AsO4)2(OH) · H2O |
| 8.CG.15 | Lotharmeyerite | CaZn2(AsO4)2 · 2H2O |
| 8.CG.15 | Nickeltsumcorite | Pb(Ni,Fe3+)2(AsO4)2(H2O,OH)2 |
| 8.CG.15 | Magnesiofluckite | CaMg(AsO3OH)2(H2O)2 |
| 8.CG.15 | Krettnichite | PbMn3+2(VO4)2(OH)2 |
| 8.CG.15 | Cobalttsumcorite | PbCo2(AsO4)2 · 2H2O |
| 8.CG.15 | Manganlotharmeyerite | CaMn3+2(AsO4)2(OH)2 |
| 8.CG.15 | Tsumcorite | PbZn2(AsO4)2 · 2H2O |
| 8.CG.15 | Ferrilotharmeyerite | CaZnFe3+(AsO4)2(OH) · H2O |
| 8.CG.15 | Cobaltlotharmeyerite | CaCo2(AsO4)2 · 2H2O |
| 8.CG.15 | Mounanaite | PbFe3+2(VO4)2(OH)2 |
| 8.CG.15 | Nickellotharmeyerite | CaNi2(AsO4)2 · 2H2O |
| 8.CG.20 | Lukrahnite | CaCuFe3+(AsO4)2(OH,H2O)2 |
| 8.CG.20 | Helmutwinklerite | PbZn2(AsO4)2 · 2H2O |
| 8.CG.20 | Phosphogartrellite | PbCuFe3+(PO4)2(OH,H2O)2 |
| 8.CG.20 | Gartrellite | PbCuFe3+(AsO4)2(OH) · H2O |
| 8.CG.20 | Zincgartrellite | PbZn2(AsO4)2(H2O,OH)2 |
| 8.CG.20 | Rappoldite | PbCo2(AsO4)2 · 2H2O |
| 8.CG.25 | Pottsite | (Pb3xBi4-2x)(VO4)4 · H2O (0.8 < x < 1.0) |
| 8.CG.25 | Armellinoite-(Ce) | Ca4Ce4+(AsO4)4 · H2O |
| 8.CG.35 | Nickeltalmessite | Ca2Ni(AsO4)2 · 2H2O |
Other Information
Thermal Behaviour:
DTA curve shows an endothermic break at 300° and an exothermic break at 730°.
Notes:
Dissolved by dilute acids.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Irhtemite
mindat.org URL:
https://www.mindat.org/min-2043.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Irhtemite
Localities for Irhtemite
Showing 10 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and 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).
All localities listed without proper references should be considered as questionable.
Czech Republic | |
| Hloušek et al. (2002) |
France | |
| Cuchet (2000) |
| Cuchet (2000) | |
Germany | |
| Weiß (1990) |
| Weiß (1990) | |
Greece | |
| Rieck et al. (2020) |
| Rieck et al. (2020) |
Morocco | |
| Favreau et al. (2006) |
| - (1974) |
USA | |
| Mineral News: 19 (12) |
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Bou Azzer mining district, Drâa-Tafilalet Region, Morocco