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Rotemite
A valid IMA mineral species
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About Rotemite
Retama raetam growing in Puntagorda, La Palma, Canary Islands
Formula:
Ca4Cr2(OH)12Cl2 · 4H2O
Colour:
pale bluish-violet
Hardness:
2½ - 3
Specific Gravity:
2.18 (Calculated)
Crystal System:
Trigonal
Member of:
Name:
The name rotemite is derived from the rotem plant (also known as retama), which commonly grows in the wadis of the Negev Desert. Rotem is a genus of blooming shrub characterized by dense clusters of small white to light purple flowers that densely overgrow the branches. Similarly, rotemite forms tiny purple crystals that cover the surface of the holotype specimen.
The first Cr-bearing member of the hydrocalumite group within the hydrotalcite supergroup.
Single-crystal X-ray diffractiuon revealed that the investigated crystals represent an unusual 6R polytype of LDH compounds with a large unit-cell parameter c, resulting from a strictly ordered structure.
Single-crystal X-ray diffractiuon revealed that the investigated crystals represent an unusual 6R polytype of LDH compounds with a large unit-cell parameter c, resulting from a strictly ordered structure.
Unique Identifiers
Mindat ID:
471492
Long-form identifier:
mindat:1:1:471492:3
Similar Names
| Rhytmite | A synonym of 'Rhythmite' |
IMA Classification of Rotemite
Approved
IMA Formula:
Ca4Cr3+2(OH)12Cl2·4H2O
Approval year:
2024
Type description reference:
Skrzyńska, Katarzyna; Müller, Harald; Juroszek, Rafał; Krüger, Biljana; Cametti, Georgia; Pakhomova, Anna; Galuskina, Irina; Vapnik, Yevgeny; Woźniak, Krzysztof; Galuskin, Evgeny (2025) Rotemite, Ca4Cr2(OH)12Cl2·4 H2O – the trigonal chromium analog of hydrocalumite and Friedel’s salt – a new mineral from the Hatrurim Complex, Israel. Applied Clay Science, 278. 108002 doi:10.1016/j.clay.2025.108002
Classification of Rotemite
4.FL.05
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
L : Hydroxides with H2O +- (OH); sheets of edge-sharing octahedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
L : Hydroxides with H2O +- (OH); sheets of edge-sharing octahedra
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 |
|---|---|---|
| Rot | 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 Rotemite
Colour:
Pale bluish-violet
Comment:
pale bluish-violet (daylight) to pinkish-violet (artificial light)
Streak:
Pale light-purple
Hardness:
2½ - 3 on Mohs scale
Cleavage:
Perfect
{0001}
{0001}
Density:
2.18 g/cm3 (Calculated)
Optical Data of Rotemite
Type:
Uniaxial (-)
RI values:
nω = 1.565(2) nε = 1.544(2)
Max. Birefringence:
δ = 0.021
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:
Low (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.
Pleochroism:
Non-pleochroic
Chemistry of Rotemite
Mindat Formula:
Ca4Cr2(OH)12Cl2 · 4H2O
Element Weights:
Crystallography of Rotemite
Crystal System:
Trigonal
Class (H-M):
3m(32/m) - Hexagonal Scalenohedral
Space Group:
R3c
Setting:
R3c
Cell Parameters:
a = 5.7944(2) Å, c = 46.69(4) Å
Ratio:
a:c = 1 : 8.058
Unit Cell V:
1,357.60 ų (Calculated from Unit Cell)
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 7.78 Å | (100) |
| 3.888 Å | (19) |
| 3.798 Å | (13) |
| 2.890 Å | (27) |
| 2.319 Å | (13) |
| 2.300 Å | (6) |
| 2.115 Å | (8) |
| 1.668 Å | (7) |
Reference:
Skrzyńska, Katarzyna; Müller, Harald; Juroszek, Rafał; Krüger, Biljana; Cametti, Georgia; Pakhomova, Anna; Galuskina, Irina; Vapnik, Yevgeny; Woźniak, Krzysztof; Galuskin, Evgeny (2025) Rotemite, Ca4Cr2(OH)12Cl2·4 H2O – the trigonal chromium analog of hydrocalumite and Friedel’s salt – a new mineral from the Hatrurim Complex, Israel. Applied Clay Science, 278. 108002 doi:10.1016/j.clay.2025.108002
Type Occurrence of Rotemite
General Appearance of Type Material:
forms tiny hexagonal plates and tabular crystals, which occur as crust-like polycrystalline aggregates of several dozen μm in size and a maximum crust thickness of 1 mm on the host rock. The dimensions of individual single crystals typically range from a few μm up to rarely exceeding 60 μm in-plane, with a maximum thickness of 20 μm
Place of Conservation of Type Material:
Type material is deposited in the collections of the Earth and Man National Museum, Cherni Vrah Blvd. 4, 1421 Sofia, Bulgaria, catalogue number 40450
Geological Setting of Type Material:
crust of aggregates on samples of rocks altered at low temperatures
Associated Minerals at Type Locality:
Reference:
Skrzyńska, Katarzyna; Müller, Harald; Juroszek, Rafał; Krüger, Biljana; Cametti, Georgia; Pakhomova, Anna; Galuskina, Irina; Vapnik, Yevgeny; Woźniak, Krzysztof; Galuskin, Evgeny (2025) Rotemite, Ca4Cr2(OH)12Cl2·4 H2O – the trigonal chromium analog of hydrocalumite and Friedel’s salt – a new mineral from the Hatrurim Complex, Israel. Applied Clay Science, 278. 108002 doi:10.1016/j.clay.2025.108002
Synonyms of Rotemite
Other Language Names for Rotemite
Relationship of Rotemite to other Species
Member of:
Other Members of Hydrotalcite Supergroup:
| Akopovaite | Al4Li2(OH)12(CO3)(H2O)3 | Mon. 2/m : B2/m |
| Amoraite | Ca12Al6(OH)36(CO3)2(SO3) · 15H2O | Tric. 1 : P1 |
| Brugnatellite | Mg6Fe3+(CO3)(OH)13 · 4H2O | Hex. |
| Carbocalumite | Ca4Al2(OH)12(CO3) · 6H2O | Trig. 3m(32/m) : R3c |
| Coalingite | Mg10Fe3+2(OH)24[CO3] · 2H2O | Trig. 3m(32/m) : R3m |
| Cualstibite Group | M2R(OH)6[Sb5+(OH)6], where M = Zn, Ni, Cu and R = Al or Fe3+ | |
| Dritsite | Li2Al4(OH)12Cl2 · 3H2O | Hex. 6/mmm(6/m2/m2/m) : P63/mcm |
| Fougèrite Group | ||
| Glaucocerinite Group | ||
| Hydrocalumite Group | ||
| Hydrotalcite Group | M6R3+2(OH)16Z · 4H2O, where M=Mg, Fe, Ni, R3+ = Al, Cr, Co or Fe, and Z=CO3, Cl | |
| Marioantofilliite | [Cu4Al2(OH)12](CO3) · 3H2O | Mon. 2/m : B2/m |
| Muskoxite | Mg7Fe4O13 · 10H2O | Trig. 3m(32/m) |
| Poellmannite | Ca6Al3(OH)18[Na(H2O)6](SO4)2 · 6H2O | Trig. 3 : R3 |
| Quintinite Group | ||
| 'UM1987-05-OH:AlCMg' | Mg4Al2(OH)12(CO3,SO4) · 3H2O | |
| Wermlandite Group | M7R3+2(OH)18[Ca(H2O)6][SO4]2 · 6H2O, where = Mg, Fe, Zn and R= Al or Fe | |
| Woodwardite Group | May be considered a subgroup of the Hydrotalcite Group. |
Common Associates
Related Minerals - Strunz-mindat Grouping
| 4.FL. | Trébeurdenite | Fe2+2Fe3+4O2(OH)10CO3 · 3H2O |
| 4.FL. | Mariakrite | [Ca4Al2(OH)12(H2O)4][Fe2S4] |
| 4.FL.05 | Muskoxite | Mg7Fe4O13 · 10H2O |
| 4.FL.05 | Jamborite | Ni2+1-xCo3+x(OH)2-x(SO4)x · nH2O |
| 4.FL.05 | Mössbauerite | Fe3+6O4(OH)8[CO3] · 3H2O |
| 4.FL.05 | Meixnerite | Mg6Al2(OH)16(OH)2 · 4H2O |
| 4.FL.05 | Woodallite | Mg6Cr2(OH)16Cl2 · 4H2O |
| 4.FL.05 | Fougèrite | Fe2+4Fe3+2(OH)12[CO3] · 3H2O |
| 4.FL.05 | Dritsite | Li2Al4(OH)12Cl2 · 3H2O |
| 4.FL.05 | Iowaite | Mg6Fe3+2(OH)16Cl2 · 4H2O |
| 4.FL.10 | Hydrocalumite | Ca4Al2(OH)12(Cl,CO3,OH)2 · 4H2O |
| 4.FL.15 | Kuzelite | Ca4Al2(OH)12[SO4] · 6H2O |
| 4.FL.20 | Jianshuiite | (Mg,Mn,Ca)Mn3O7 · 3H2O |
| 4.FL.20 | Ernienickelite | NiMn3O7 · 3H2O |
| 4.FL.20 | Aurorite | Mn2+Mn4+3O7 · 3H2O |
| 4.FL.20 | Chalcophanite | ZnMn4+3O7 · 3H2O |
| 4.FL.25 | Woodruffite | Zn2+x/2(Mn4+1-xMn3+x)O2 · yH2O |
| 4.FL.30 | Asbolane | (Ni,Co)2-xMn4+(O,OH)4 · nH2O |
| 4.FL.30 va | 'Lampadite' | Cu, Mn, O, H |
| 4.FL.35 | Buserite | Na4Mn14O27 · 21H2O |
| 4.FL.40 | Takanelite | (Mn,Ca)Mn4O9 · H2O |
| 4.FL.40 | Ranciéite | (Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O |
| 4.FL.45 | Birnessite | (Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O |
| 4.FL.55 | Cianciulliite | Mn(Mg,Mn)2Zn2(OH)10 · 2-4H2O |
| 4.FL.60 | Jensenite | Cu3[TeO6] · 2H2O |
| 4.FL.65 | Leisingite | Cu2MgTe6+O6 · 6H2O |
| 4.FL.70 | Magnesiohongruiite-(Fe3+) | (Mg2Fe3+)Fe3+NbO7(OH) |
| 4.FL.70 | Akdalaite | Al10O14(OH)2 |
| 4.FL.75 | Cafetite | CaTi2O5 · H2O |
| 4.FL.80 | Mourite | UMo5O12(OH)10 |
| 4.FL.85 | Deloryite | Cu4(UO2)(MoO4)2(OH)6 |
| 4.FL.90 | Lagalyite | Ca2xMn1-xO2 · 1.5-2H2O |
| 4.FL.95 | 'Tunnerite' | |
| 4.FL.100 | Carbocalumite | Ca4Al2(OH)12(CO3) · 6H2O |
| 4.FL.100 | Mampsisite | Ca4Al2(CO3)(OH)12 · 5H2O |
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 Rotemite
mindat.org URL:
https://www.mindat.org/min-471492.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Rotemite
Reference List:
Skrzyńska, K., Krüger, B., Juroszek, R., Cametti, G., Pakhomova, A., Kaproń, G., Galuskina, I., Vapnik, Y., Woźniak, K., Galuskin, E. V (2024) Rotemite, IMA 2024-058, in IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) – Newsletter 82. European Journal of Mineralogy, 36 (6). 1005-1010 doi:10.5194/ejm-36-1005-2024
Skrzyńska, Katarzyna; Müller, Harald; Juroszek, Rafał; Krüger, Biljana; Cametti, Georgia; Pakhomova, Anna; Galuskina, Irina; Vapnik, Yevgeny; Woźniak, Krzysztof; Galuskin, Evgeny (2025) Rotemite, Ca4Cr2(OH)12Cl2·4 H2O – the trigonal chromium analog of hydrocalumite and Friedel’s salt – a new mineral from the Hatrurim Complex, Israel. Applied Clay Science, 278. 108002 doi:10.1016/j.clay.2025.108002
Localities for Rotemite
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.
Israel (TL) | |
| Skrzyńska et al. (2024) +1 other reference |
Quick NavTopAbout RotemiteUnique IdentifiersSimilar NamesIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Halamish Quarry, Hatrurim Basin, Tamar Regional Council, Beersheba Subdistrict, Southern District, Israel