Decrespignyite-(Y)
A valid IMA mineral species
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About Decrespignyite-(Y)
Formula:
Cu(Y,REE)4(CO3)4(OH)5Cl · 2H2O
Colour:
Bright royal blue to pale blue
Lustre:
Vitreous, Pearly
Hardness:
4
Specific Gravity:
3.64
Crystal System:
Monoclinic
Name:
Honouring Robert James Champion de Crespigny (b. 1950), Chairman of Normandy Mining Ltd. and Chairman of the South Australian Museum, for his contributions to Australian education.
This page provides mineralogical data about Decrespignyite-(Y).
Unique Identifiers
Mindat ID:
9294
Long-form identifier:
mindat:1:1:9294:0
IMA Classification of Decrespignyite-(Y)
Classification of Decrespignyite-(Y)
5.CC.35
5 : CARBONATES (NITRATES)
C : Carbonates without additional anions, with H2O
C : With rare earth elements (REE)
5 : CARBONATES (NITRATES)
C : Carbonates without additional anions, with H2O
C : With rare earth elements (REE)
16a.1.11.1
16a : ANHYDROUS CARBONATES CONTAINING HYDROXYL OR HALOGEN
1 : (AB)(XO3)Zq
16a : ANHYDROUS CARBONATES CONTAINING HYDROXYL OR HALOGEN
1 : (AB)(XO3)Zq
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 |
|---|---|---|
| Dcp-Y | 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 Decrespignyite-(Y)
Vitreous, Pearly
Colour:
Bright royal blue to pale blue
Streak:
Pale blue
Hardness:
4 on Mohs scale
Comment:
Estimated
Fracture:
None observed
Density:
3.64 g/cm3 (Measured) 3.645 g/cm3 (Calculated)
Optical Data of Decrespignyite-(Y)
Type:
Biaxial (-)
RI values:
nα = 1.604(4) nγ = 1.638(3)
Max. Birefringence:
δ = 0.034
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:
High (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 biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (89°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (89°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Pleochroism:
Visible
Comments:
Medium strong; X very pale bluish, Y and Z bluish (with greenish tint)
Chemistry of Decrespignyite-(Y)
Mindat Formula:
Cu(Y,REE)4(CO3)4(OH)5Cl · 2H2O
Element Weights:
Crystallography of Decrespignyite-(Y)
Crystal System:
Monoclinic
Cell Parameters:
a = 8.899(6) Å, b = 22.77(2) Å, c = 8.589(6) Å
β = 120.06(5)°
β = 120.06(5)°
Ratio:
a:b:c = 0.391 : 1 : 0.377
Unit Cell V:
1506.3 ų
Z:
4
Morphology:
As crusts, coatings and fillings in thin fissures on the slatey country rock.
Comment:
powder Diffraction data indicate the space group is P2, Pm or P2/m. New data by Rius et al. (2020) suggest space group P-3m1 and a= 8.5462(2), c= 22.731(2) Å, but these authors cannot exclude monoclinic symmetry and their model contains several partially occupied sites (disorder is indicated by streaks).
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 22.79 Å | (30) |
| 7.463 Å | (30) |
| 7.086 Å | (50) |
| 6.241 Å | (100) |
| 4.216 Å | (30) |
| 3.530 Å | (40) |
| 3.336 Å | (30) |
| 2.143 Å | (30) |
Type Occurrence of Decrespignyite-(Y)
General Appearance of Type Material:
Blue crusts, coatings and fillings in thin fissures. Crusts and spherulitic aggregates are composed of individual tiny pseudohexagonal, often curved platelets.
Synonyms of Decrespignyite-(Y)
Other Language Names for Decrespignyite-(Y)
Common Associates
Associations Based on Photo Data:
| 21 photos of Decrespignyite-(Y) associated with Kamphaugite-(Y) | Ca(Y,REE)(CO3)2(OH) · H2O |
| 9 photos of Decrespignyite-(Y) associated with Malachite | Cu2(CO3)(OH)2 |
| 7 photos of Decrespignyite-(Y) associated with Tengerite-(Y) | Y2(CO3)3 · 2-3H2O |
| 2 photos of Decrespignyite-(Y) associated with Donnayite-(Y) | NaCaSr3Y(CO3)6 · 3H2O |
| 2 photos of Decrespignyite-(Y) associated with Alicewilsonite-(YLa) | Na2Sr2YLa(CO3)6 · 3H2O |
| 2 photos of Decrespignyite-(Y) associated with Calcite | CaCO3 |
Related Minerals - Strunz-mindat Grouping
| 5.CC. | Bainbridgeite-(NdCe) | Na2Ba2NdCe(CO3)6 · 3H2O |
| 5.CC. | Yuchuanite-(Y) | Y2(CO3)3 · H2O |
| 5.CC. | Alicewilsonite-(YCe) | Na2Sr2YCe(CO3)6 · 3H2O |
| 5.CC.05 | Donnayite-(Y) | NaCaSr3Y(CO3)6 · 3H2O |
| 5.CC.05 | Alicewilsonite-(YLa) | Na2Sr2YLa(CO3)6 · 3H2O |
| 5.CC.05 | Mckelveyite-(Nd) | NaCaBa3Nd(CO3)6 · 3H2O |
| 5.CC.05 | Mckelveyite-(Y) | NaCaBa3Y(CO3)6 · 3H2O |
| 5.CC.05 | Ewaldite | Ba(Na,Ca,Y,Ce,K)(CO3)2 · 2.6H2O |
| 5.CC.05 | 'UM1992-05-CO:CaCeLaNaSr' | (Sr,Na,Y,REE,Ca,Ba)2(CO3)2 · H2O |
| 5.CC.05 | Weloganite | Na2Sr3Zr(CO3)6 · 3H2O |
| 5.CC.05 | Mckelveyite Group | A3B3(CO3)6 · 3H2O |
| 5.CC.05 | Bainbridgeite-(YCe) | Na2Ba2YCe(CO3)6 · 3H2O |
| 5.CC.05 | 'Unnamed (MSH UK-37A)' | Sr3NaCaY(CO3)6 · 3H2O |
| 5.CC.10 | Tengerite-(Y) | Y2(CO3)3 · 2-3H2O |
| 5.CC.15 | Lokkaite-(Y) | Ca(Y,Gd,Nd,Dy)4(CO3)7 · 9H2O |
| 5.CC.15 | Kimuraite-(Y) | Ca(Y,Nd)2(CO3)4 · 6H2O |
| 5.CC.15 | Hizenite-(Y) | Ca2Y6(CO3)11 · 14H2O |
| 5.CC.20 | Shomiokite-(Y) | Na3Y[CO3]3 · 3H2O |
| 5.CC.25 | Lanthanite-(Ce) | Ce2(CO3)3 · 8H2O |
| 5.CC.25 | Lanthanite-(La) | La2(CO3)3 · 8H2O |
| 5.CC.25 | Lanthanite-(Nd) | Nd2(CO3)3 · 8H2O |
| 5.CC.25 | Calkinsite-(Ce) | (Ce,La)2(CO3)3 · 4H2O |
| 5.CC.30 | Adamsite-(Y) | NaY[CO3]2 · 6H2O |
| 5.CC.40 | Galgenbergite-(Ce) | Ca(Ce,La,Nd)2(CO3)4 · H2O |
| 5.CC.45 | Lecoqite-(Y) | Na3Y(CO3)3 · 6H2O |
Other Information
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 Decrespignyite-(Y)
mindat.org URL:
https://www.mindat.org/min-9294.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Decrespignyite-(Y)
Reference List:
Wallwork, K.; Kolitsch, U.; Pring, A.; Nasdala, L. (2002) Decrespignyite-(Y), a new copper yttrium rare earth carbonate chloride hydrate from Paratoo, South Australia. Mineralogical Magazine, 66 (1). 181-188 doi:10.1180/0026461026610021
Frost, Ray L., Palmer, Sara J. (2011) Raman spectrum of decrespignyite [(Y,REE)4Cu(CO3)4Cl(OH)5·2H2O] and its relation with those of other halogenated carbonates including bastnasite, hydroxybastnasite, parisite and northupite. Journal of Raman Spectroscopy, 42 (11). 2042-2048 doi:10.1002/jrs.2959
Rius, Jordi, Colombo, Fernando, Vallcorba, Oriol, Torrelles, Xavier, Gemmi, Mauro, Mugnaioli, Enrico (2020) Structural study of decrespignyite-(Y), a complex yttrium rare earth copper carbonate chloride, by three-dimensional electron and synchrotron powder diffraction. European Journal of Mineralogy, 32 (5) 545-555 doi:10.5194/ejm-32-545-2020
Localities for Decrespignyite-(Y)
Showing 1 localities.
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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.
Australia (TL) | |
| Kolitsch et al. (2026) +2 other references |
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Paratoo copper mine, Paratoo, District Council of Peterborough, South Australia, Australia