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Oxycalciomicrolite

A valid IMA mineral species
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03826310017869965073783.jpg
Oxycalciomicrolite

Timmerhult, Orust, VÃĪstra GÃķtaland County, Sweden
04360390017870670464115.jpg
Oxycalciomicrolite

Timmerhult, Orust, VÃĪstra GÃķtaland County, Sweden
03826310017869965073783.jpg
Oxycalciomicrolite

Timmerhult, Orust, VÃĪstra GÃķtaland County, Sweden
04360390017870670464115.jpg
Oxycalciomicrolite

Timmerhult, Orust, VÃĪstra GÃķtaland County, Sweden
03826310017869965073783.jpg
Oxycalciomicrolite

Timmerhult, Orust, VÃĪstra GÃķtaland County, Sweden
05254440017870490571819.jpg
Oxycalciomicrolite

Timmerhult, Orust, VÃĪstra GÃķtaland County, Sweden
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About OxycalciomicroliteHide

Formula:
Ca2Ta2O6O
Also given as Ca2Ta2O7.
Colour:
Brownish-yellow to brownish-red
Lustre:
Vitreous, Resinous
Hardness:
5 - 5½
Specific Gravity:
6.333 (Calculated)
Crystal System:
Isometric
Name:
Named for being the oxygen- and calcium-dominant member of the microlite group.
The Ca- and oxide-dominant member of the group. Approved in 2020.

Analyses published (Christy & Atencio, 2013).


Unique IdentifiersHide

Mindat ID:
40355
Long-form identifier:
mindat:1:1:40355:9

IMA Classification of OxycalciomicroliteHide

Classification of OxycalciomicroliteHide

Strunz-mindat (2026):
4.DH.15

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
H : With large (+- medium-sized) cations; sheets of edge-sharing octahedra

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

Physical Properties of OxycalciomicroliteHide

Lustre:
Vitreous, Resinous
Transparency:
Translucent
Colour:
Brownish-yellow to brownish-red
Streak:
White
Hardness:
5 - 5½ on Mohs scale
Tenacity:
Brittle
Cleavage:
None Observed
Parting:
None observed
Density:
6.333 g/cm3 (Calculated)

Optical Data of OxycalciomicroliteHide

Type:
Isotropic
RI values:
n = 2.037
Surface Relief:
Very High (positive)
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

Chemistry of OxycalciomicroliteHide

Mindat Formula:
Ca2Ta2O6O

Also given as Ca2Ta2O7.
Element Weights:
Element% weight
Ta65.319 %
O20.214 %
Ca14.467 %

Calculated from ideal end-member formula.
Ta
O
Ca
Elements listed:
Ca, O, Ta - search for minerals with similar chemistry

Crystallography of OxycalciomicroliteHide

Crystal System:
Isometric
Class (H-M):
m3m(4/m32/m) - Hexoctahedral
Space Group:
Fd3m
Setting:
Fd3m
Cell Parameters:
a = 10.4325(4) Å
Unit Cell V:
1135.46 ÅÂģ
Z:
8

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
6.023 Å(89)
3.145 Å(44)
3.011 Å(100)
2.608 Å(25)
2.008 Å(14)
1.844 Å(48)
1.763 Å(11)
1.573 Å(33)

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Stage 4b: Highly evolved igneous rocks>3.0
34 : Complex granite pegmatites

Type Occurrence of OxycalciomicroliteHide

Synonyms of OxycalciomicroliteHide

Other Language Names for OxycalciomicroliteHide

Relationship of Oxycalciomicrolite to other SpeciesHide

Member of:
Microlite Group > Pyrochlore Supergroup
Other Members of Microlite Group:
Fluorcalciomicrolite(Ca,Na)2(Ta,Nb)2O6FIso. m3m(4/m32/m) : Fd3m
Fluornatromicrolite(Na1.5Bi0.5)Ta2O6FIso. m3m(4/m32/m) : Fd3m
Hydrokenomicrolite(â—ŧ,H2O)2Ta2(O,OH)6(H2O)Iso. m3m(4/m32/m)
'Hydromicrolite'(H2O,â—ŧ)2Ta2(O,OH)6(H2O)
HydroxycalciomicroliteCa1.5Ta2O6(OH)Iso. 432 : P4232
Hydroxykenomicrolite(â—ŧ,Na,Sb3+)2Ta2O6(OH,Cs)Iso. m3m(4/m32/m) : Fd3m
'Hydroxylstibiomicrolite'(Sb,Ca,Na)2(Ta,Nb)2O6(OH)Iso.
'Hydroxynatromicrolite'(Na,Bi3+,â—ŧ)2Ta2O6(OH)Iso. m3m(4/m32/m) : Fd3m
Kenomicroliteâ—ŧ2Ta2[O4(OH)2]â—ŧIso. m3m(4/m32/m) : Fd3m
Kenoplumbomicrolite(Pb,â—ŧ)2Ta2O6(â—ŧ,OH,O)Iso. m3m(4/m32/m) : Fd3m
Oxybismutomicrolite(Bi1.33â—ŧ0.67)ÎĢ2Ta2O6OIso. m3m(4/m32/m) : Fd3m
OxystannomicroliteSn2Ta2O6OIso. m3m(4/m32/m) : Fd3m
Oxystibiomicrolite(Sb3+,Ca)2Ta2O6OIso. m3m(4/m32/m) : Fd3m
'Uranmicrolite (of Hogarth 1977)'(Ca,U,Na)2-x(Ta,Nb)2(O,OH)7Iso.
'Yttromicrolite (of Hogarth)'(Ca,Y3+,U,Na)2-x(Ta,Nb,Ti,Fe3+)2O7Iso. m3m(4/m32/m) : Fd3m

Common AssociatesHide

Associations Based on Photo Data:
1 photo of Oxycalciomicrolite associated with Monazite-(Sm)Sm(PO4)
1 photo of Oxycalciomicrolite associated with Monazite-(Nd)Nd(PO4)
1 photo of Oxycalciomicrolite associated with Columbite-(Mn)Mn2+Nb2O6
1 photo of Oxycalciomicrolite associated with Columbite-(Fe)Fe2+Nb2O6
1 photo of Oxycalciomicrolite associated with CassiteriteSnO2
1 photo of Oxycalciomicrolite associated with Pyrochlore GroupA2Nb2(O,OH)6Z
1 photo of Oxycalciomicrolite associated with UraniniteUO2
1 photo of Oxycalciomicrolite associated with ZirconZr(SiO4)

Related Minerals - Strunz-mindat GroupingHide

4.DH.Cesiokenopyrochloreâ—ŧNb2(O,OH)6(Cs,â—ŧ) Iso. m3m(4/m32/m) : Fd3m
4.DH.RomÃĐite GroupA2(Sb5+)2O6Z
4.DH.OxyplumboromÃĐitePb2Sb2O6OIso. m3m(4/m32/m) : Fd3m
4.DH.Fluornatropyrochlore(Na,Pb,Ca,REE,U)2Nb2O6FIso. m3m(4/m32/m)
4.DH.Hydroxykenomicrolite(â—ŧ,Na,Sb3+)2Ta2O6(OH,Cs)Iso. m3m(4/m32/m) : Fd3m
4.DH.'FluornatroromÃĐite'(Na,Ca)2Sb2(O,OH)6F
4.DH.Oxyyttrobetafite-(Y)Y2Ti2O6OIso. m3m(4/m32/m) : Fd3m
4.DH.05Thorutite(Th,U,Ca)Ti2(O,OH)6Mon.
4.DH.05OrthobranneriteU4+U6+Ti4O12(OH)2Orth.
4.DH.05BranneriteUTi2O6Mon. 2/m : B2/m
4.DH.10KassiteCaTi2O4(OH)2Mon. 2/m : P21/c
4.DH.10Lucasite-(La)Mon. 2 : B2
4.DH.10Lucasite-(Ce)CeTi2(O,OH)6Mon.
4.DH.15'Fluorhydropyrochlore'
4.DH.15Hydrokenoelsmoreiteâ—ŧ2W2O6(H2O)Iso. m3m(4/m32/m) : Fd3m
4.DH.15'Hydroxynatromicrolite'(Na,Bi3+,â—ŧ)2Ta2O6(OH)Iso. m3m(4/m32/m) : Fd3m
4.DH.15Hydroplumboelsmoreite(Pb,â—ŧ)(W,Fe3+)2O6 · H2OIso. m3m(4/m32/m) : Fd3m
4.DH.15Hydropyrochlore(H2O,â—ŧ)2Nb2(O,OH)6(H2O)Iso. m3m(4/m32/m) : Fd3m
4.DH.15'Unnamed (Sb-analogue of Hydroxymanganopyrochlor)'(Mn,Ca,Y)2(Sb,Ti)2O6(OH)
4.DH.15Hydroxynatropyrochlore(Na,Ca,Ce)2Nb2O6(OH)Iso. m3m(4/m32/m) : Fd3m
4.DH.15Hydrokenopyrochlore(â—ŧ,x)2Nb2O6(H2O,Cs)Iso. m3m(4/m32/m) : Fd3m
4.DH.15Oxybismutomicrolite(Bi1.33â—ŧ0.67)ÎĢ2Ta2O6OIso. m3m(4/m32/m) : Fd3m
4.DH.15Kenomicroliteâ—ŧ2Ta2[O4(OH)2]â—ŧIso. m3m(4/m32/m) : Fd3m
4.DH.15Fluornatromicrolite(Na1.5Bi0.5)Ta2O6FIso. m3m(4/m32/m) : Fd3m
4.DH.15'Oxynatropyrochlore'(Na,Ca,U)2Nb2O6(O,OH)
4.DH.15Hydroxycalciopyrochlore(Ca,Na,U,â—ŧ)2(Nb,Ti)2O6(OH)Iso. m3m(4/m32/m) : Fd3m
4.DH.15Fluorcalciopyrochlore(Ca,Na)2(Nb,Ti)2O6FIso. m3m(4/m32/m) : Fd3m
4.DH.15OxycalciopyrochloreCa2Nb2O6OIso. m3m(4/m32/m) : Fd3m
4.DH.15'Fluorstrontiopyrochlore'(Sr,â—ŧ)2Nb2(O,OH)6F
4.DH.15OxyplumbopyrochlorePb2Nb2O6OIso. m3m(4/m32/m) : Fd3m
4.DH.15'Fluorplumbopyrochlore'(Pb,Y,Th,U,Na,Ca)2-x(Nb,Ti)2O6FIso.
4.DH.15'Bismutomicrolite (of Hogarth 1977)'Iso. m3m(4/m32/m) : Fd3m
4.DH.15'Bismutopyrochlore (of Chukanov et al.)'(Bi,Ca,U,Pb)2-xNb2(O,OH)6(OH)Amor.
4.DH.15'Kenoplumbopyrochlore'(Pb,â—ŧ)Nb2O6(â—ŧ,O)
4.DH.15Hydroxyplumbopyrochlore (Pb1.5â—ŧ0.5)Nb2O6(OH)Iso. m3m(4/m32/m) : Fd3m
4.DH.15'Stibiomicrolite (of Groat et al.)'
4.DH.15'Oxyyttropyrochlore-(Y)'(Y,â—ŧ)2Nb2O6O
4.DH.15'Fluorkenopyrochlore'(â—ŧ,Sr,Ce,Ca,Na)2(Nb,Ti)2O6F
4.DH.15HydroxycalciomicroliteCa1.5Ta2O6(OH)Iso. 432 : P4232
4.DH.15'Strontiopyrochlore (of Hogarth 1977)'(Sr,Ce,Ca)0.66(Nb,Fe)2(O,OH)7
4.DH.15 va'Alumotungstite'â—ŧ2W2O6(H2O)Iso. m3m(4/m32/m) : Fd3m
4.DH.15'Oxycalciobetafite'Ca2(Ti,Nb)2O6O
4.DH.15'Oxyuranobetafite'(U,Ca,â—ŧ)2(Ti,Nb)2O6O
4.DH.15Fluorcalciomicrolite(Ca,Na)2(Ta,Nb)2O6FIso. m3m(4/m32/m) : Fd3m
4.DH.15OxystannomicroliteSn2Ta2O6OIso. m3m(4/m32/m) : Fd3m
4.DH.15Kenoplumbomicrolite(Pb,â—ŧ)2Ta2O6(â—ŧ,OH,O)Iso. m3m(4/m32/m) : Fd3m
4.DH.15Oxynatromicrolite(Na,Ca,U)2(Ta,Nb)2O6(O,F)Iso. m3m(4/m32/m) : Fd3m
4.DH.15Oxystibiomicrolite(Sb3+,Ca)2Ta2O6OIso. m3m(4/m32/m) : Fd3m
4.DH.15'Hydromicrolite'(H2O,â—ŧ)2Ta2(O,OH)6(H2O)
4.DH.15'Plumbomicrolite (of Hogarth 1977)'
4.DH.15Hydrokenomicrolite(â—ŧ,H2O)2Ta2(O,OH)6(H2O)Iso. m3m(4/m32/m)
4.DH.15Hydroxykenoelsmoreite(â—ŧ,Pb)2(W,Fe3+,Al)2(O,OH)6(OH)Trig. 3 : R3
4.DH.15 va'Yttromicrolite (of Hogarth)'(Ca,Y3+,U,Na)2-x(Ta,Nb,Ti,Fe3+)2O7Iso. m3m(4/m32/m) : Fd3m
4.DH.15Hydroxykenopyrochlore(â—ŧ,Ce,Ba)2(Nb,Ti)2O6(OH,F)Iso. m3m(4/m32/m) : Fd3m
4.DH.15Hydroxymanganopyrochlore(Mn2+,Th,Na,Ca,REE)2(Nb,Ti)2O6(OH)Iso. m3m(4/m32/m) : Fd3m
4.DH.20'CuproromÃĐite'Cu2Sb2(O,OH)7Iso.
4.DH.20HydroxycalcioromÃĐite(Ca,Sb3+)2(Sb5+,Ti)2O6(OH)Iso. m3m(4/m32/m) : Fd3m
4.DH.20BindheimitePb2Sb2O6OIso. m3m(4/m32/m) : Fd3m
4.DH.20HydroxyferroromÃĐite(Fe2+1.5â—ŧ0.5)Sb5+2O6(OH)Iso. m3m(4/m32/m) : Fd3m
4.DH.20FluorcalcioromÃĐite(Ca,Na,â—ŧ)2Sb5+2(O,OH)6FIso. m3m(4/m32/m) : Fd3m
4.DH.20OxycalcioromeĖiteCa2Sb2O6OIso. m3m(4/m32/m) : Fd3m
4.DH.20StetefeldtiteAg2Sb2(O,OH)7Iso.
4.DH.20StibiconiteSb3+Sb5+2O6(OH)Iso. m3m(4/m32/m) : Fd3m
4.DH.20MonimolitePb2Sb5+2O7Iso. m3m(4/m32/m)
4.DH.25RosiaitePbSb5+2O6Trig. 3m(32/m) : P31m
4.DH.30Stefanweissite(Ca,REE)2Zr2(Nb,Ti)(Ti,Nb)2Fe2+O14Orth. mmm(2/m2/m2/m) : Cmca
4.DH.30ZirconoliteCaZrTi2O7Orth.
4.DH.30Laachite(Ca,Mn)2Zr2Nb2TiFeO14Mon. 2/m : B2/b
4.DH.30NÃķggerathite-(Ce)(Ce,Ca)2Zr2(Nb,Ti)(Ti,Nb)2Fe2+O14Orth. mmm(2/m2/m2/m) : Cmca
4.DH.35LiandratiteU(Nb,Ta)2O8Trig. 3m(32/m) : P31m
4.DH.35PetscheckiteUFe(Nb,Ta)2O8Hex.
4.DH.40IngersoniteCa3Mn2+Sb5+4O14Trig. 32 : P3121
4.DH.45PittongiteNa0.22(W,Fe3+)(O,OH)3 · 0.44H2OHex. 6m2 : P6m2
4.DH.50TazzoliiteBa4-xNaxTi2Nb3SiO17[PO2(OH)2]x(OH)(1-2x) Orth. mmm(2/m2/m2/m) : Fmmm

Other InformationHide

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 OxycalciomicroliteHide

References for OxycalciomicroliteHide

Reference List:
ČernÃ―, Petr, Chapman, Ron, Ferreira, Karen, Smeds, Sten-Anders (2004) Geochemistry of oxide minerals of Nb, Ta, Sn, and Sb in the VarutrÃĪsk granitic pegmatite, Sweden: The case of an “anomalous” columbite-tantalite trend. American Mineralogist, 89 (4) 505-518 doi:10.2138/am-2004-0405[as "stibiomicrolite"]
Atencio, D., Andrade, M. B., Christy, A. G., Giere, R., Kartashov, P. M. (2010) The pyrochlore supergroup of minerals: nomenclature. The Canadian Mineralogist, 48 (3) 673-698 doi:10.3749/canmin.48.3.673
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2013) New minerals and nomenclature modifications approved in 2013. CNMNC Newsletter No 18. Mineralogical Magazine, 77 (8) 3249-3258 doi:10.1180/minmag.2013.077.8.15
Christy, A. G., Atencio, D. (2013) Clarification of status of species in the pyrochlore supergroup. Mineralogical Magazine, 77 (1) 13-20 doi:10.1180/minmag.2013.077.1.02
Miyawaki, Ritsuro, Hatert, FrÃĐdÃĐric, Pasero, Marco, Mills, Stuart J. (2020) IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) - Newsletter 54. European Journal of Mineralogy, 32 (2) 275-283 doi:10.5194/ejm-32-275-2020
Menezes da Silva, Victor H.R., Ávila, Ciro A., Neumann, Reiner, Faulstich, Fabiano R.L., Alves, Felipe E.A., de Almeida, Filipe B., Cidade, Tais Proença, Sousa, Sarah Siqueira da Cruz GuimarÃĢes (2020) Oxycalciomicrolite, (Ca,Na)2(Ta,Nb,Ti)2O6(O,F), a new member of the microlite group (pyrochlore supergroup) from the Paleoproterozoic SÃĢo JoÃĢo del Rei Pegmatite Province, Minas Gerais state, Brazil. Mineralogical Magazine, 84 (6) 854-858 doi:10.1180/mgm.2020.74
(2022) Oxycalciomicrolite. Handbook of Mineralogy. Mineralogical Society of America

Localities for OxycalciomicroliteHide

Showing 12 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
 
  • Minas Gerais
    • Governador Valadares
      • Golconda mining district
Andrade (2007)
    • Nazareno
Menezes da Silva et al. (2020) +1 other reference
Italy
 
  • Lombardy
    • Lecco Province
      • Colico
        • Piona Peninsula
Vignola et al. (2011)
  • Piedmont
    • Verbano-Cusio-Ossola Province
      • Druogno
        • Orcesco
Guastoni et al. (2008) +2 other references
      • Toceno
        • Val di Crana
          • Val di Crana pegmatites
Vignola et al. (2018)
      • Trontano
        • Pizzo Marcio
Menezes da Silva et al. (2020)
Menezes da Silva et al. (2020)
Menezes da Silva et al. (2020)
Mozambique
 
  • Zambezia Province
    • Alto Ligonha Pegmatite Field
      • GilÃĐ district
MnhnL collection
Sweden
 
  • VÃĪsterbotten County
    • SkellefteÃĨ
ČernÃ― et al. (2004) +1 other reference
  • VÃĪstra GÃķtaland County
    • Orust
Knut Eldjarn Collection Similar specimen from the locality in the NRM (Stockholm)
USA
 
  • Virginia
    • Amelia County
      • Amelia (Amelia Court House)
Duresky et al. (2025)
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