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Almeidaite

A valid IMA mineral species
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03232960017272472263750.jpg
Almeidaite

Paulo de Mudo claim, Novo Horizonte, Bahia, Brazil
06213800017272324668059.jpg
Almeidaite

Paulo de Mudo claim, Novo Horizonte, Bahia, Brazil
02235370017272324679948.jpg
Almeidaite

Paulo de Mudo claim, Novo Horizonte, Bahia, Brazil
06041340017271994575060.jpg
Almeidaite

Paulo de Mudo claim, Novo Horizonte, Bahia, Brazil
06213800017272324668059.jpg
Almeidaite

Paulo de Mudo claim, Novo Horizonte, Bahia, Brazil
02235370017272324679948.jpg
Almeidaite

Paulo de Mudo claim, Novo Horizonte, Bahia, Brazil
01171610017272472285367.jpg
Almeidaite

Paulo de Mudo claim, Novo Horizonte, Bahia, Brazil
06213800017272324668059.jpg
Almeidaite

Paulo de Mudo claim, Novo Horizonte, Bahia, Brazil
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About AlmeidaiteHide

05215180017272472284925.jpg
Prof. Fernando Flávio Marques de Almeida (1916-2013)
Formula:
PbZn2(Mn,Y)(Ti,Fe3+)18O37(OH,O)
Colour:
Black
Lustre:
Sub-Metallic
Specific Gravity:
4.68
Crystal System:
Trigonal
Name:
Named in 2013 by Luiz Albert Diaz Menezes Filho, L.A.D., N.V. Chukanov, Ramiza K. Rastsvetaeva, S.M. Aksenov, Igor Viktorovich Pekov, M.L.S.C. Chaves, R. Scholz, Daniel Atencio, P.R.G. Brandão, A.W. Romano, L.C.A. de Oliveira, J.D. Ardisson, K. Krambrock, R.L. Moreira, F.S. Guimarães, A.C. Persiano, and R. P. Richards in honor of Prof. Fernando Flávio Marques de Almeida [February 18, 1916 Rio de Janeiro, Brazil - August 2, 2013 São Paulo, Brazil]. Flávio Marques de Almeida is considered to be one of the most important Brazilian geologists. He was professor of geology at Institute for Technological Research, São Paulo about 1938-1939 until 1974. He became professor at the Institute of Geosciences, University of São Paulo, He was one of the founders of the Brazilian Society of Geology and the first chief editor of the Journal of Geology. His honors include: Vice-President of Géologique Société de France (1971); Medal Jose Bonifacio - Society Brazilian Geology (1964), Grand Cross of the National Order of Scientific Merit (1995), Doctor Honoris Causa State University of Campinas (1991), Medal of Merit Council Federal Engineering and Architecture (1995).
The Zn analogue of senaite and Pb analogue of landauite. ZnMn-analogue of cleusonite. PbZn-analogue of crichtonite. Chemically somewhat similar to nežilovite.

Almeidaite is a member of the crichtonite group with Pb dominant in the A site (with 12-fold coordination, located in the cubic layer, M0) and Zn dominant in the T site (with 4-fold, i.e., tetrahedral coordination). The anionic cp (close packed) framework has 9 layers along c in the chhchh sequence.



Unique IdentifiersHide

Mindat ID:
43884
Long-form identifier:
mindat:1:1:43884:7

IMA Classification of AlmeidaiteHide

Classification of AlmeidaiteHide

Strunz-mindat (2026):
4.00.

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
0 :
0 :

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

SymbolSourceReference for Standard
AmdIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43

Physical Properties of AlmeidaiteHide

Lustre:
Sub-Metallic
Transparency:
Opaque
Colour:
Black
Streak:
Brown
Tenacity:
Brittle
Cleavage:
None Observed
Parting:
No parting
Fracture:
Conchoidal
Density:
4.68(5) g/cm3 (Measured)    4.616 g/cm3 (Calculated)

Optical Data of AlmeidaiteHide

Type:
Uniaxial (+)
Reflectivity:
WavelengthR1 (%)R2 (%)
400nm12.84%15.45%
420nm12.79%15.39%
440nm12.77%15.36%
460nm12.79%15.35%
470nm12.78%15.39%
480nm12.80%15.39%
500nm12.77%15.34%
520nm12.83%15.41%
540nm12.84%15.41%
546nm12.86%15.43%
560nm12.89%15.48%
580nm12.85%15.42%
589nm12.91%15.55%
600nm12.96%15.63%
620nm12.99%15.67%
640nm13.02%15.73%
650nm13.04%15.75%
660nm13.09%15.81%
680nm13.11%15.86%
700nm13.16%15.94%


Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 15.94%.
R1 shown in black, R2 shown in red

Chemistry of AlmeidaiteHide

Mindat Formula:
PbZn2(Mn,Y)(Ti,Fe3+)18O37(OH,O)
Element Weights:
Element% weight
Ti46.236 %
O32.626 %
Pb11.119 %
Zn7.017 %
Mn2.948 %
H0.054 %

Calculated from ideal end-member formula.
Ti
O
Pb
Zn
Mn
H
Elements listed:
Fe, H, Mn, O, Pb, Ti, Y, Zn - search for minerals with similar chemistry
Common Impurities:
Fe,Y,Sr,(Ca,La)

Crystallography of AlmeidaiteHide

Crystal System:
Trigonal
Class (H-M):
3 - Rhombohedral
Space Group:
R3
Cell Parameters:
a = 10.4359(2) Å, c = 21.0471(4) Å
Ratio:
a:c = 1 : 2.017
Unit Cell V:
1985.1 ų
Z:
3
Morphology:
Platy crystals flattened on [0001],dominated by the basal pinacoid {0001}, which is bounded by various, mostly steep, rhombohedra and the hexagonal prism {1120}.
Twinning:
Multiply twinned, with non-planar contact surfaces that are approximately parallel to the c axis.

Crystal StructureHide

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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0020510AlmeidaiteKastsvetaeva R K, Aksenov S M, Chukanov N V, Menezes L A D (2014) Crystal structure of almeidaite, a new mineral of the crichtonite group Doklady Chemistry 455 53-572014Novo Horizonte, Bahia, Brazil0293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Near-surface Processes
23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47)
High-? alteration and/or metamorphism
32 : Ba/Mn/Pb/Zn deposits, including metamorphic deposits
Stage 4b: Highly evolved igneous rocks>3.0
35 : Ultra-alkali and agpaitic igneous rocks

Type Occurrence of AlmeidaiteHide

Synonyms of AlmeidaiteHide

Other Language Names for AlmeidaiteHide

French:Almeidaite
German:Almeidait
Norwegian:Almeidaitt

Relationship of Almeidaite to other SpeciesHide

Member of:
Crichtonite Group
Other Members of Crichtonite Group:
BotuobinskiteSrFe2+Mg2(Cr3+6Ti4+12)[O36(OH)2]Trig. 3 : R3
Cleusonite(Pb,Sr)(U4+,U6+)(Fe2+,Zn)2(Ti,Fe2+,Fe3+)18(O,OH)38Trig. 3 : R3
CrichtoniteSr(Mn,Y,U)Fe2(Ti,Fe,Cr,V)18(O,OH)38Trig. 3 : R3
Davidite-(Ce)Ce(Y,U)Fe2(Ti,Fe,Cr,V)18(O,OH,F)38Trig. 3 : R3
Davidite-(La)La(Y,U)Fe2(Ti,Fe,Cr,V)18(O,OH,F)38Trig. 3 : R3
'Davidite-(Y)'(La,Ce,Na,Ca,Pb)(Y,Fe2+,◻)(Fe2+,Mn2+)2(Ti,Fe3+,Nb,Zr)18O38 (hypothetical)Trig.
Dessauite-(Y)(Sr,Pb)(Y,U)(Ti,Fe3+)20O38Trig. 3 : R3
Gramaccioliite-(Y)(Pb,Sr)(Y,Mn)Fe3+2(Ti,Fe3+)18O38Trig. 3 : R3
Haitaite-(La)LaU4+Fe3+2(Ti13Fe2+4Fe3+)O38Trig. 3 : R3
LandauiteNaMnZn2(Ti,Fe)6Ti12O38Trig. 3 : R3
Lindsleyite(Ba,Sr)(Zr,Ca)(Fe,Mg)2(Ti,Cr,Fe)18O38Trig.
Loveringite(Ca,Ce,La)(Zr,Fe)(Mg,Fe)2(Ti,Fe,Cr,Al)18O38Trig. 3 : R3
Mapiquiroite(Sr,Pb)(U,Y)Fe2(Ti,Fe3+,Cr3+)18O38Trig. 3 : R3
Mathiasite(Mg,Cr,Fe,Ca,K)2(Ti,Zr,Cr,Fe)5O12Trig. 3 : R3
Mianningite(◻,Pb,Ce,Na)(U4+,Mn,U6+)Fe3+2 (Ti,Fe3+)18O38Trig. 3 : R3
MirnyiteSrZr4+Mg2(Cr3+6Ti4+12)O38Trig. 3 : R3
PaseroitePbMn2+(Mn2+,Fe3+)2(V5+,Ti,◻)18O38 Trig. 3 : R3
SaranovskiteSrCaFe2+2(Cr4Ti2)Ti12O38Trig. 3 : R3
SenaitePb(Mn,Y,U)(Fe,Zn)2(Ti,Fe,Cr,V)18(O,OH)38Trig. 3 : R3
'UM1987-03-O:FePbTiU'~(U,Pb)(Ti,Fe3+,Fe2+,Mn)21O38Trig. 3 : R3
'UM2003-08-O:AlCaFeREEScTiV'(Ca,Ce)Sc(Ti,V,Fe,Al)20O38
'UM2006-05-O:CaFeKMnNaREESrTiZr'(Sr,Na,K,REE)(Ca,Zr,Mn)(Ti,Fe)18Fe2O38
'UM2006-06-O:CaFeKMnNaREESrTiZr'(Sr,Na,K,REE)(Zr,Ca,Mn)(Ti,Fe)18Fe2O38
'UM2006-07-O:CaFeKMnNaREESrTiZr'(Na,Sr,K,REE)(Ca,Zr,Mn)(Ti,Fe)18Fe2O38
'UM2006-08-O:CaFeKMnNaREESrTiZr'(Na,Sr,K,REE)(Zr,Ca,Mn)(Ti,Fe)18Fe2O38
'UM2006-09-O:CaFeMnREESrTiZr'(Ce,Sr,REE)(Ca,Mn,Zr)Fe2(Ti,Fe)18O38
'Unnamed (HBU UK-4)'NaFe2+Zn2(Ti,Fe3+,Nb)6Ti12O38Trig. 3 : R3

Related Minerals - Strunz-mindat GroupingHide

4.00.Ferrotaaffeite-6N'3S(Be,Zn,Mg)FeAl4O8Trig. 3m(32/m) : R3m
4.00.Mapiquiroite(Sr,Pb)(U,Y)Fe2(Ti,Fe3+,Cr3+)18O38Trig. 3 : R3
4.00.'UM2004-19-O:AlCeGdZr'(Gd,Ce)4Al2Zr4O17
4.00.VapnikiteCa2CaUO6Mon. 2/m : P21/c
4.00.Microlite GroupA2-mTa2X6-wZ1-nIso. m3m(4/m32/m) : Fd3m
4.00.Bismutostibiconite(Bi,Fe3+,◻)2Sb5+2O7Iso. m3m(4/m32/m) : Fd3m
4.00.'UM2004-21-O:CaFeGdZr'Ca2Gd4Fe5ZrO15
4.00.'UM2004-27-O:GdTi'Gd2Ti4O11
4.00.Písekite-(Y)(Y,As,Ca,Fe,U)(Nb,Ti,Ta)O4
4.00.Pyrochlore GroupA2Nb2(O,OH)6Z
4.00.20Yttrotungstite-(Nd)NdW2O7(OH) · H2OMon. 2/m : P21/m
4.00.25HeisenbergiteU6+O2(OH)2 · H2OOrth.

Fluorescence of AlmeidaiteHide

In UV light:
Non-fluorescent in long-wave or short-wave UV

Other InformationHide

IR Spectrum:
The main absorption bands of the IR spectrum (cm-1, s = strong, sh = shoulder, w = weak) are: 3340 (O-H stretching vibrations), 1099w, 1041w, 1012w (overtones and Zn-OH bending vibrations), 695sh, 574s, 534s, 485sh (stretching vibrations in octahedra and tetrahedra).
Notes:
Metamict due to trace Th; Mössbauer spectroscopy indicates almost all Fe is trivalent.
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 AlmeidaiteHide

References for AlmeidaiteHide

Reference List:
Kartashov P.M., Troneva N.V., Mokhov A.V., Kovalenko V.I., Tsareva G.M. (1993): Defective zinc-bearing senaite from Khaldzan-Buregteg rare-metal alkali granites, Mongolian Altai. Transactions (Doklady) Russ. Acad. Sci., Earth Science Section: 333A(9): 93-97.
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2013) New minerals and nomenclature modifications approved in 2013. CNMNC Newsletter No 16. Mineralogical Magazine, 77 (6) 2695-2709 doi:10.1180/minmag.2013.077.6.01
Rastsvetaeva, R. K., Aksenov, S. M., Chukanov, N. V., Menezes, L. A. D. (2014) Crystal structure of almeidaite, a new mineral of the crichtonite group. Doklady Chemistry, 455 (1-2). 53-57 doi:10.1134/s0012500814040016
Menezes Filho, Luiz A. D., Chukanov, Nikita V., Rastsvetaeva, Ramiza K., Aksenov, Sergey M., Pekov, Igor V., Chaves, Mário L. S. C., Richards, R. Peter, Atencio, Daniel, Brandão, Paulo R. G., Scholz, Ricardo, Krambrock, Klaus, Moreira, Roberto L., Guimarães, Frederico S., Romano, Antônio W., Persiano, Aba C., de Oliveira, Luiz C. A., Ardisson, José D. (2015) Almeidaite, Pb(Mn,Y)Zn2(Ti,Fe3+)18O36(O,OH)2, a new crichtonite-group mineral, from Novo Horizonte, Bahia, Brazil. Mineralogical Magazine, 79 (2) 269-283 doi:10.1180/minmag.2015.079.2.06
Belakovskiy, Dmitriy I., Uvarova, Yulia, Gagne, Olivier C. (2016) New Mineral Names. American Mineralogist, 101 (4) 1012-1019 doi:10.2138/am-2016-nmn10149
(2016) Almeidaite. Handbook of Mineralogy. Mineralogical Society of America

Localities for AlmeidaiteHide

Showing 7 localities.

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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Locality ListHide

- 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). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.
Brazil (TL)
 
  • Bahia
    • Novo Horizonte
Menezes (n.d.) +2 other references
  • Minas Gerais
Menezes Filho et al. (2015)
Mongolia
 
  • Khovd Province
    • Myangad District
Kartashov P.M. et al. (1993)
North Macedonia
 
  • Čaška Municipality
    • Nežilovo
      • Jakupica Mountains
        • Babuna Valley
Galuskina et al. (2026)
Ermolaeva et al. (2017)
Chukanov et al. (2015)
Chukanov et al. (2018) +2 other references
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