Iraqite-(La)
A valid IMA mineral species
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About Iraqite-(La)
Flag of Iraq
Formula:
KCa2(La,Ce,Th)Si8O20
Colour:
Pale greenish yellow
Lustre:
Pearly, Dull
Hardness:
4½
Specific Gravity:
3.27
Crystal System:
Tetragonal
Member of:
Name:
Originally named simply iraqite, for the country in which it was discovered, Iraq. The suffix was added by the International Mineralogical Association (IMA) at a later date to indicate the dominant rare-earth-element (REE).
This page provides mineralogical data about Iraqite-(La).
Unique Identifiers
Mindat ID:
2041
Long-form identifier:
mindat:1:1:2041:7
Similar Names
| Iranite | A valid IMA mineral species | Pb10Cu(CrO4)6(SiO4)2(OH)2 |
IMA Classification of Iraqite-(La)
Approved
IMA Formula:
KCa2(La,Ce3+,Th4+)Si8O20
Approval year:
1973
First published:
1976
Classification of Iraqite-(La)
9.CH.10
9 : SILICATES (Germanates)
C : Cyclosilicates
H : [Si4O12]8- 4-membered double rings
9 : SILICATES (Germanates)
C : Cyclosilicates
H : [Si4O12]8- 4-membered double rings
63.1.1.2
63 : CYCLOSILICATES Condensed Rings
1 : Condensed Rings (Steacyite group)
63 : CYCLOSILICATES Condensed Rings
1 : Condensed Rings (Steacyite group)
14.8.8
14 : Silicates not Containing Aluminum
8 : Silicates of Group III metals other than Al
14 : Silicates not Containing Aluminum
8 : Silicates of Group III metals other than Al
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 |
|---|---|---|
| Irq-La | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Iraqite-(La)
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Iraqite-(La)
Pearly, Dull
Transparency:
Translucent
Colour:
Pale greenish yellow
Streak:
Whitish
Hardness:
4½ on Mohs scale
Hardness:
VHN100=245 - 314 - Vickers
Cleavage:
Distinct/Good
Two good cleavages and a third poor cleavage
Two good cleavages and a third poor cleavage
Fracture:
Irregular/Uneven
Density:
3.27 g/cm3 (Measured) 3.28 g/cm3 (Calculated)
Comment:
Berman balance, correcting for minor impurities and non-structural water
Optical Data of Iraqite-(La)
Type:
Uniaxial (-)
RI values:
nω = 1.590 nε = 1.585
Max. Birefringence:
δ = 0.005
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 (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized uniaxial interference figure - the conoscopic
(convergent-light, Bertrand-lens-in) view, for a grain cut with the optic axis
centred and vertical. The coloured rings are isochromatics, computed with the
same physics as the Michel-Lévy bar above; the dark cross is the isogyre.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
For a genuinely uniaxial mineral viewed this way, that cross stays perfectly stationary if you rotate the stage - unlike a biaxial mineral, where it splits apart on rotation. That invariance is itself the standard diagnostic test for telling uniaxial and biaxial minerals apart at the microscope.
Comments:
anomalously biaxial
Chemistry of Iraqite-(La)
Mindat Formula:
KCa2(La,Ce,Th)Si8O20
Element Weights:
Crystallography of Iraqite-(La)
Crystal System:
Tetragonal
Class (H-M):
4/mmm(4/m2/m2/m) - Ditetragonal Dipyramidal
Space Group:
P4/mcc
Setting:
P4/mcc
Cell Parameters:
a = 7.61(1) Å, c = 14.72(2) Å
Ratio:
a:c = 1 : 1.934
Unit Cell V:
852.47 ų (Calculated from Unit Cell)
Z:
1
Morphology:
Anhedral, massive.
Comment:
(by analogy to ekanite).
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.28 Å | (100) |
| 3.31 Å | (100) |
| 2.64 Å | (100) |
| 7.36 Å | (80) |
| 3.38 Å | (80) |
| 3.40 Å | (60) |
| 2.17 Å | (40) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| High-? alteration and/or metamorphism | |
| 31 : Thermally altered carbonate, phosphate, and iron formations |
Type Occurrence of Iraqite-(La)
Place of Conservation of Type Material:
The Natural History Museum, London, England, 1973,481; National School of Mines, Paris, France.
Synonyms of Iraqite-(La)
Other Language Names for Iraqite-(La)
Dutch:Iraqiet-(La)
German:Iraqit-(La)
Irakit-(La)
Irakit-(La)
Relationship of Iraqite-(La) to other Species
Member of:
Other Members of Steacyite Group:
| Arapovite | (K1-x◻x)(Ca,Na)2U4+Si8O20 (x ~ 0.5) | Tet. 4/mmm(4/m2/m2/m) : P4/mcc |
| Steacyite | K0.3(Na,Ca)2ThSi8O20 | Tet. 4/mmm(4/m2/m2/m) : P4/mcc |
| Turkestanite | (K,◻)(Ca,Na)2ThSi8O20 · nH2O | Tet. 4/mmm(4/m2/m2/m) : P4/mcc |
Related Minerals - Strunz-mindat Grouping
| 9.CH.05 | Khvorovite | (Pb,Ba,K)4Ca2[Si8B2(Si,B)2O28]F |
| 9.CH.05 | Guastoniite-(Y) | Pb4(YCa)(Si8B4O28)F |
| 9.CH.05 | Kapitsaite-(Y) | (Ba,K,Pb)4(Y,Ca)2Si8(B,Si)4O28F |
| 9.CH.05 | Hyalotekite | (Ba,Pb,K)4(Ca,Y)2(B,Be)2(Si,B)2Si8O28(F,Cl) |
| 9.CH.05 | Itsiite | Ba4Ca2[Si8B4O28]◻ |
| 9.CH.10 | Arapovite | (K1-x◻x)(Ca,Na)2U4+Si8O20 (x ~ 0.5) |
| 9.CH.10 | Steacyite | K0.3(Na,Ca)2ThSi8O20 |
| 9.CH.10 | Turkestanite | (K,◻)(Ca,Na)2ThSi8O20 · nH2O |
Radioactivity
Radioactivity:
| Element | % Content | Activity (Bq/kg) | Radiation Type |
|---|---|---|---|
| Uranium (U) | 0.0000% | 0 | α, β, γ |
| Thorium (Th) | 0.0000% | 0 | α, β, γ |
| Potassium (K) | 4.8700% | 1,510 | β, γ |
For comparison:
- Banana: ~15 Bq per fruit
- Granite: 1,000–3,000 Bq/kg
- EU exemption limit: 10,000 Bq/kg
Note: Risk is shown relative to daily recommended maximum exposure to non-background radiation of 1000 µSv/year. Note that natural background radiation averages around 2400 µSv/year so in reality these risks are probably extremely overstated! With infrequent handling and safe storage natural radioactive minerals do not usually pose much risk.
Interactive Simulator:
Note: The mass selector refers to the mass of radioactive mineral present, not the full specimen, also be aware that the matrix may also be radioactive, possibly more radioactive than this mineral!
Activity: –
| Distance | Dose rate | Risk |
|---|---|---|
| 1 cm | ||
| 10 cm | ||
| 1 m |
The external dose rate (D) from a radioactive mineral is estimated by summing the gamma radiation contributions from its Uranium, Thorium, and Potassium content, disregarding daughter-product which may have a significant effect in some cases (eg 'pitchblende'). This involves multiplying the activity (A, in Bq) of each element by its specific gamma ray constant (Γ), which accounts for its unique gamma emissions. The total unshielded dose at 1 cm is then scaled by the square of the distance (r, in cm) and multiplied by a shielding factor (μshield). This calculation provides a 'worst-case' or 'maximum risk' estimate because it assumes the sample is a point source and entirely neglects any self-shielding where radiation is absorbed within the mineral itself, meaning actual doses will typically be lower. The resulting dose rate (D) is expressed in microsieverts per hour (μSv/h).
D = ((AU × ΓU) + (ATh × ΓTh) + (AK × ΓK)) / r2 × μshield
Fluorescence of Iraqite-(La)
None (LW or SW)
Other Information
Notes:
Insoluble in both cold and hot hydrochloric, sulphuric, and nitric 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 Iraqite-(La)
mindat.org URL:
https://www.mindat.org/min-2041.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Iraqite-(La)
Reference List:
Livingstone, A., Atkin, D., Hutchison, D., Al-Hermezi, H. M. (1976) Iraqite, a new rare-earth mineral of the ekanite group. Mineralogical Magazine, 40 (313) 441-445 doi:10.1180/minmag.1976.040.313.02
Fleischer, Michael, Pabst, Adolf, Cabri, Louis J. (1976) New Mineral Names. American Mineralogist, 61 (9-10) 1053-1056
Livingstone, A., Atkin, D., Hutchison, D., Al-Hermezi, H. M. (1976) Iraqite, a new rare-earth mineral of the ekanite group. Mineralogical Magazine, 40 (313) 441-445 doi:10.1180/minmag.1976.040.313.02
Localities for Iraqite-(La)
Showing 1 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.
Iraq (TL) | |
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Shakhi-Rash Mountain, Hero, Qaladiza, Pshdar District, Sulaymaniyah Governorate, Iraq