Talmessite
A valid IMA mineral species
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About Talmessite
Formula:
Ca2Mg(AsO4)2 · 2H2O
Colour:
White, colorless, translucent pale green (nickel-bearing), brownish pink (cobalt-bearing)
Lustre:
Vitreous
Hardness:
5
Specific Gravity:
3.421
Crystal System:
Triclinic
Member of:
Name:
Named after its discovery locality, the Talmessi Mine, Iran.
Dimorph of:
Unique Identifiers
Mindat ID:
3876
Long-form identifier:
mindat:1:1:3876:4
IMA Classification of Talmessite
Approved
IMA Formula:
Ca2Mg(As5+O4)2·2H2O
First published:
1960
Classification of Talmessite
8.CG.05
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
40.2.2.5
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
2 : AB2(XO4)2·xH2O
40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
2 : AB2(XO4)2·xH2O
20.2.18
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.
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 |
|---|---|---|
| Tlm | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Tlm | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Pronunciation of Talmessite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Talmessite
Vitreous
Transparency:
Translucent
Colour:
White, colorless, translucent pale green (nickel-bearing), brownish pink (cobalt-bearing)
Streak:
White
Hardness:
5 on Mohs scale
Cleavage:
None Observed
Density:
3.421 g/cm3 (Measured) 3.53 g/cm3 (Calculated)
Optical Data of Talmessite
Type:
Biaxial (-)
RI values:
nα = 1.672 nβ = 1.685 nγ = 1.698
2V:
Measured: 90° , Calculated: 88°
Max. Birefringence:
δ = 0.026
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:
Very 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.
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.
Dispersion:
r > v strong
Chemistry of Talmessite
Mindat Formula:
Ca2Mg(AsO4)2 · 2H2O
Element Weights:
Crystallography of Talmessite
Crystal System:
Triclinic
Class (H-M):
1 - Pinacoidal
Space Group:
P1
Cell Parameters:
a = 5.874(7) Å, b = 6.943(11) Å, c = 5.537(6) Å
α = 97.3(1)°, β = 108.7(1)°, γ = 108.1(2)°
α = 97.3(1)°, β = 108.7(1)°, γ = 108.1(2)°
Ratio:
a:b:c = 0.846 : 1 : 0.797
Unit Cell V:
196.76 ų (Calculated from Unit Cell)
Z:
1
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) |
|---|---|---|---|---|---|---|---|
| 0012065 | Talmessite | Catti M, Ferraris G, Ivaldi G (1977) Hydrogen bonding in the crystalline state. Structure of talmessite, Ca2(Mg,Co)(AsO4)2*2H2O, and crystal chemistry of related minerals Bulletin de Mineralogie 100 230-236 | 1977 | Bou-Azzer, Morocco | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.09 Å | (60) |
| 4.62 Å | (40) |
| 3.56 Å | (60) |
| 3.21 Å | (80) |
| 3.07 Å | (100) |
| 2.77 Å | (100) |
| 1.717 Å | (60) |
Comments:
Talmessi mine, Iran. Nearly identical to pattern of anorthoroselite.
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] |
Type Occurrence of Talmessite
General Appearance of Type Material:
Pale green crystals, less than 0.1 mm.
Place of Conservation of Type Material:
National School of Mines, Paris, France; The Natural History Museum, London, England.
Geological Setting of Type Material:
Oxidation zone of a Cu-Ni-Co deposit.
Associated Minerals at Type Locality:
Synonyms of Talmessite
Other Language Names for Talmessite
Varieties of Talmessite
| Cobalt-bearing Talmessite | A cobalt-bearing variety of talmessite. |
| Nickel-bearing Talmessite | A Ni-bearing variety of talmessite. Ni-dominant compositions correspond to nickeltalmessite. |
Relationship of Talmessite to other Species
Member of:
Other Members of Collinsite Group:
| Anorthoroselite | Ca2Co(AsO4)2 · 2H2O | Tric. |
| Cassidyite | Ca2Ni(PO4)2 · 2H2O | Tric. |
| Collinsite | Ca2Mg(PO4)2 · 2H2O | Tric. 1 : P1 |
| Fairfieldite | Ca2Mn2+(PO4)2 · 2H2O | Tric. 1 : P1 |
| Gaitite | Ca2Zn(AsO4)2 · 2H2O | Tric. 1 : P1 |
| Hillite | Ca2Zn(PO4)2 · 2H2O | Tric. 1 : P1 |
| Messelite | Ca2Fe2+(PO4)2 · 2H2O | Tric. 1 : P1 |
| Nickeltalmessite | Ca2Ni(AsO4)2 · 2H2O | Tric. 1 : P1 |
| Parabrandtite | Ca2Mn2+(AsO4)2 · 2H2O | Tric. 1 : P1 |
| 'Unnamed (Fe2+-analogue of Parabrandtite)' | Ca2Fe2+(AsO4)2 · 2H2O |
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 26 photos of Talmessite associated with Calcite | CaCO3 |
| 24 photos of Talmessite associated with Erythrite | Co3(AsO4)2 · 8H2O |
| 23 photos of Talmessite associated with Austinite | CaZn(AsO4)(OH) |
| 16 photos of Talmessite associated with Cobaltaustinite | CaCo(AsO4)(OH) |
| 12 photos of Talmessite associated with Vladimirite | Ca4(AsO4)2(AsO3OH) · 4H2O |
| 9 photos of Talmessite associated with Roselite | Ca2Co(AsO4)2 · 2H2O |
| 9 photos of Talmessite associated with Aragonite | CaCO3 |
| 8 photos of Talmessite associated with Heterogenite | Co3+O(OH) |
| 6 photos of Talmessite associated with Dolomite | CaMg(CO3)2 |
| 6 photos of Talmessite associated with Wendwilsonite | Ca2Mg(AsO4)2 · 2H2O |
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 | 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 |
| 8.CG.55 | Irhtemite | Ca4Mg(AsO4)2(HAsO4)2 · 4H2O |
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 Talmessite
mindat.org URL:
https://www.mindat.org/min-3876.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Talmessite
Reference List:
Bariand, Pierre, Herpin, Paulette (1960) Un arséniate de calcium et de magnésium, isomorphe de la β rosélite. Bulletin de Minéralogie, 83 (4) 118-121 doi:10.3406/bulmi.1960.5390
Pierrot, Roland (1964) Contribution à la minéralogie des arséniates calciques et calcomagnésiens naturels. Bulletin de Minéralogie, 87 (2) 169-211 doi:10.3406/bulmi.1964.5727
Catti, Michele, Ferraris, Giovanni, Ivaldi, Gabriella (1977) Hydrogen bonding in the crystalline state. Structure of talmessite, Ca2 (Mg, Co) (As O4)2.2H2O, and crystal chemistry of related minerals. Bulletin de Minéralogie, 100 (3) 230-236 doi:10.3406/bulmi.1977.7140
Nickel, Ernest H., Mandarino, Joseph A. (1987) Procedures involving the IMA Commission on New Minerals and Mineral Names and guidelines on mineral nomenclature. American Mineralogist, 72 (9-10) 1031-1042
Joswig, W., Paulus, E. F., Liebscher, B. (2004) Crystal structure of dicalcium (cobalt, magnesium) diarsenate dihydrate, Ca2(Co0.532Mg0.468)[AsO4]2 · 2H2O, hydrogen bonding in talmessite. Zeitschrift für Kristallographie - New Crystal Structures, 219 (1) 341-342 doi:10.1524/ncrs.2004.219.14.373
Frost, Ray L. (2009) Raman and infrared spectroscopy of arsenates of the roselite and fairfieldite mineral subgroups. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 71 (5) 1788-1794 doi:10.1016/j.saa.2008.06.039
Localities for Talmessite
Showing 65 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.
Austria | |
| Meixner et al. (1979) +1 other reference |
Chile | |
| samples analysed by Jochen Schlüter |
| Samples analysed by Tony Kampf of LAC ... |
| Yang et al. (2018) |
| Yang et al. (2011) |
| samples analysed by Gerhard Mohn and ... | |
| Samples analysed by Dr. Jochen Schlüter (Hamburg University) +1 other reference |
| samples analysed by Anthony Kampf +2 other references |
China | |
| Shen (n.d.) |
Czech Republic | |
| Hloušek et al. (2002) |
France | |
| Wittern et al. (1997) |
| Bari (1982) | |
| Feraud et al. (1976) +1 other reference |
| R. Pierrot | |
Germany | |
| Walenta (2001) |
| Weiß (1990) |
| Weiß (1990) | |
| Lapis 30 (7/8) |
Greece | |
| Branko Rieck and Karl-Heinz Fabritz ... +1 other reference |
Hungary | |
| Szakáll et al. (1996) |
| Szakáll et al. (1996) |
| collection: Herman Ottó Museum |
Iran (TL) | |
| Bariand et al. (1960) +2 other references |
Italy | |
| Balestra et al. (2006) |
| Kolitsch et al. (2011) |
Japan | |
| OHNISHI et al. (2013) +1 other reference |
Kyrgyzstan | |
| Karpenko et al. (2025) |
Morocco | |
| Meisser et al. (2006) |
| Favreau et al. (2006) |
| [var: Cobalt-bearing Talmessite, var: Nickel-bearing Talmessite] Favreau et al. (2006) |
| [var: Cobalt-bearing Talmessite] Favreau et al. (2006) | |
| Analyses for Jordi Frabre |
| Favreau et al. (2007) | |
| [var: Nickel-bearing Talmessite] Favreau et al. (2006) | |
| [var: Cobalt-bearing Talmessite, var: Nickel-bearing Talmessite] Favreau et al. (2006) | |
| Georges FAVREAU collection & EDX ... | |
| [var: Nickel-bearing Talmessite] Favreau et al. (2006) | |
| [var: Nickel-bearing Talmessite] Favreau et al. (2006) | |
| Favreau et al. (2006) | |
| Favreau et al. (2006) | |
| [var: Cobalt-bearing Talmessite] Favreau et al. (2001) | |
| Favreau et al. (2006) |
| Favreau et al. (2006) |
| Favreau et al. (2007) |
| Favreau et al. (2006) | |
Namibia | |
| analysed - EDS & SXRD +1 other reference |
North Macedonia | |
| Đorđević et al. (2021) |
Spain | |
| Rewitzer et al. (2018) |
| Calvo Rebollar et al. (2022) |
Switzerland | |
| |
UK | |
| Braithwaite et al. (1996) |
USA | |
| Onac +2 other references |
| Wenrich (1988) +1 other reference |
| Marek Chorazewicz (2019) |
| Kokinos et al. (1993) |
| Kokinos et al. (1993) |
Quick NavTopAbout TalmessiteUnique IdentifiersIMA Classification Classification Mineral SymbolsPronunciation Physical Properties Optical Data Chemistry Crystallography Crystal StructureX-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesVarietiesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Ightem Mine, Ightem, Tansifte Caïdat, Agdz Cercle, Zagora Province, Drâa-Tafilalet Region, Morocco