Oxycalciomicrolite
A valid IMA mineral species
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About Oxycalciomicrolite
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
Member of:
Name:
Named for being the oxygen- and calcium-dominant member of the microlite group.
Type Locality:
The Ca- and oxide-dominant member of the group. Approved in 2020.
Analyses published (Christy & Atencio, 2013).
Analyses published (Christy & Atencio, 2013).
Unique Identifiers
Mindat ID:
40355
Long-form identifier:
mindat:1:1:40355:9
IMA Classification of Oxycalciomicrolite
Approved
IMA Formula:
Ca2Ta5+2O7
Approval year:
2019
First published:
2020
Type description reference:
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 Guimarães (2020) Oxycalciomicrolite, (Ca,Na)2(Ta,Nb,Ti)2O6(O,F), a new member of the microlite group (pyrochlore supergroup) from the Paleoproterozoic São João del Rei Pegmatite Province, Minas Gerais state, Brazil. Mineralogical Magazine, 84 (6) 854-858 doi:10.1180/mgm.2020.74
Classification of Oxycalciomicrolite
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
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 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 |
|---|---|---|
| Ocmic | 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 Oxycalciomicrolite
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 Oxycalciomicrolite
Type:
Isotropic
RI values:
n = 2.037
Surface Relief:
Very High
Chemistry of Oxycalciomicrolite
Mindat Formula:
Ca2Ta2O6O
Also given as Ca2Ta2O7.
Also given as Ca2Ta2O7.
Element Weights:
Elements listed:
Crystallography of Oxycalciomicrolite
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 ų
Z:
8
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 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 Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Type Occurrence of Oxycalciomicrolite
General Appearance of Type Material:
Octahedral crystals, ranging from 0.2 to 0.5 mm in size.
Place of Conservation of Type Material:
Mineralogical collections of the Museu Nacional, Universidade Federal do Rio de Janeiro, Quinta da Boa Vista s/n, 20940-040 Rio de Janeiro, Brazil, registration number MN-7601-M
Geological Setting of Type Material:
Pegmatite
Associated Minerals at Type Locality:
Reference:
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 Guimarães (2020) Oxycalciomicrolite, (Ca,Na)2(Ta,Nb,Ti)2O6(O,F), a new member of the microlite group (pyrochlore supergroup) from the Paleoproterozoic São João del Rei Pegmatite Province, Minas Gerais state, Brazil. Mineralogical Magazine, 84 (6) 854-858 doi:10.1180/mgm.2020.74
Synonyms of Oxycalciomicrolite
Calciomicrolite (in part)
Other Language Names for Oxycalciomicrolite
Dutch:Oxycalciomicroliet
German:Oxycalciomikrolith
Relationship of Oxycalciomicrolite to other Species
Member of:
Other Members of Microlite Group:
| Fluorcalciomicrolite | (Ca,Na)2(Ta,Nb)2O6F | Iso. m3m(4/m32/m) : Fd3m |
| Fluornatromicrolite | (Na1.5Bi0.5)Ta2O6F | Iso. m3m(4/m32/m) : Fd3m |
| Hydrokenomicrolite | (◻,H2O)2Ta2(O,OH)6(H2O) | Iso. m3m(4/m32/m) |
| 'Hydromicrolite' | (H2O,◻)2Ta2(O,OH)6(H2O) | |
| Hydroxycalciomicrolite | Ca1.5Ta2O6(OH) | Iso. 432 : P4232 |
| Hydroxykenomicrolite | (◻,Na,Sb3+)2Ta2O6(OH,Cs) | Iso. m3m(4/m32/m) : Fd3m |
| 'Hydroxylstibiomicrolite' | (Sb,Ca,Na)2(Ta,Nb)2O6(OH) | Iso. |
| 'Hydroxynatromicrolite' | (Na,Bi3+,◻)2Ta2O6(OH) | Iso. m3m(4/m32/m) : Fd3m |
| Kenomicrolite | ◻2Ta2[O4(OH)2]◻ | Iso. m3m(4/m32/m) : Fd3m |
| Kenoplumbomicrolite | (Pb,◻)2Ta2O6(◻,OH,O) | Iso. |
| Oxybismutomicrolite | (Bi1.33◻0.67)Σ2Ta2O6O | Iso. m3m(4/m32/m) : Fd3m |
| Oxystannomicrolite | Sn2Ta2O6O | Iso. m3m(4/m32/m) : Fd3m |
| Oxystibiomicrolite | (Sb3+,Ca)2Ta2O6O | Iso. m3m(4/m32/m) : Fd3m |
| 'Uranmicrolite (of Hogarth 1977)' | (Ca,U,Na)2-x(Ta,Nb)2(O,OH)7 | Iso. |
| 'Yttromicrolite (of Hogarth)' | (Ca,Y3+,U,Na)2-x(Ta,Nb,Ti,Fe3+)2O7 | Iso. m3m(4/m32/m) : Fd3m |
Common Associates
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 Cassiterite | SnO2 |
| 1 photo of Oxycalciomicrolite associated with Pyrochlore Group | A2Nb2(O,OH)6Z |
| 1 photo of Oxycalciomicrolite associated with Uraninite | UO2 |
| 1 photo of Oxycalciomicrolite associated with Zircon | Zr(SiO4) |
Related Minerals - Strunz-mindat Grouping
| 4.DH. | Cesiokenopyrochlore | ◻Nb2(O,OH)6(Cs,◻) |
| 4.DH. | Roméite Group | A2(Sb5+)2O6Z |
| 4.DH. | Oxyplumboroméite | Pb2Sb2O6O |
| 4.DH. | Fluornatropyrochlore | (Na,Pb,Ca,REE,U)2Nb2O6F |
| 4.DH. | Hydroxykenomicrolite | (◻,Na,Sb3+)2Ta2O6(OH,Cs) |
| 4.DH. | 'Fluornatroroméite' | (Na,Ca)2Sb2(O,OH)6F |
| 4.DH. | Oxyyttrobetafite-(Y) | Y2Ti2O6O |
| 4.DH.05 | Thorutite | (Th,U,Ca)Ti2(O,OH)6 |
| 4.DH.05 | Orthobrannerite | U4+U6+Ti4O12(OH)2 |
| 4.DH.05 | Brannerite | UTi2O6 |
| 4.DH.10 | Kassite | CaTi2O4(OH)2 |
| 4.DH.10 | Lucasite-(La) | |
| 4.DH.10 | Lucasite-(Ce) | CeTi2(O,OH)6 |
| 4.DH.15 | 'Fluorhydropyrochlore' | |
| 4.DH.15 | Hydrokenoelsmoreite | ◻2W2O6(H2O) |
| 4.DH.15 | 'Hydroxynatromicrolite' | (Na,Bi3+,◻)2Ta2O6(OH) |
| 4.DH.15 | Hydroplumboelsmoreite | (Pb,◻)(W,Fe3+)2O6 · H2O |
| 4.DH.15 | Hydropyrochlore | (H2O,◻)2Nb2(O,OH)6(H2O) |
| 4.DH.15 | 'Unnamed (Sb-analogue of Hydroxymanganopyrochlor)' | (Mn,Ca,Y)2(Sb,Ti)2O6(OH) |
| 4.DH.15 | Hydroxynatropyrochlore | (Na,Ca,Ce)2Nb2O6(OH) |
| 4.DH.15 | Hydrokenopyrochlore | (◻,x)2Nb2O6(H2O,Cs) |
| 4.DH.15 | Oxybismutomicrolite | (Bi1.33◻0.67)Σ2Ta2O6O |
| 4.DH.15 | Kenomicrolite | ◻2Ta2[O4(OH)2]◻ |
| 4.DH.15 | Fluornatromicrolite | (Na1.5Bi0.5)Ta2O6F |
| 4.DH.15 | 'Oxynatropyrochlore' | (Na,Ca,U)2Nb2O6(O,OH) |
| 4.DH.15 | Hydroxycalciopyrochlore | (Ca,Na,U,◻)2(Nb,Ti)2O6(OH) |
| 4.DH.15 | Fluorcalciopyrochlore | (Ca,Na)2(Nb,Ti)2O6F |
| 4.DH.15 | Oxycalciopyrochlore | Ca2Nb2O6O |
| 4.DH.15 | 'Fluorstrontiopyrochlore' | (Sr,◻)2Nb2(O,OH)6F |
| 4.DH.15 | Oxyplumbopyrochlore | Pb2Nb2O6O |
| 4.DH.15 | 'Fluorplumbopyrochlore' | (Pb,Y,Th,U,Na,Ca)2-x(Nb,Ti)2O6F |
| 4.DH.15 | 'Bismutomicrolite (of Hogarth 1977)' | |
| 4.DH.15 | 'Bismutopyrochlore (of Chukanov et al.)' | (Bi,Ca,U,Pb)2-xNb2(O,OH)6(OH) |
| 4.DH.15 | 'Kenoplumbopyrochlore' | (Pb,◻)Nb2O6(◻,O) |
| 4.DH.15 | Hydroxyplumbopyrochlore | (Pb1.5◻0.5)Nb2O6(OH) |
| 4.DH.15 | 'Stibiomicrolite (of Groat et al.)' | |
| 4.DH.15 | 'Oxyyttropyrochlore-(Y)' | (Y,◻)2Nb2O6O |
| 4.DH.15 | 'Fluorkenopyrochlore' | (◻,Sr,Ce,Ca,Na)2(Nb,Ti)2O6F |
| 4.DH.15 | Hydroxycalciomicrolite | Ca1.5Ta2O6(OH) |
| 4.DH.15 | 'Strontiopyrochlore (of Hogarth 1977)' | (Sr,Ce,Ca)0.66(Nb,Fe)2(O,OH)7 |
| 4.DH.15 va | 'Alumotungstite' | ◻2W2O6(H2O) |
| 4.DH.15 | 'Oxycalciobetafite' | Ca2(Ti,Nb)2O6O |
| 4.DH.15 | 'Oxyuranobetafite' | (U,Ca,◻)2(Ti,Nb)2O6O |
| 4.DH.15 | Fluorcalciomicrolite | (Ca,Na)2(Ta,Nb)2O6F |
| 4.DH.15 | Oxystannomicrolite | Sn2Ta2O6O |
| 4.DH.15 | Kenoplumbomicrolite | (Pb,◻)2Ta2O6(◻,OH,O) |
| 4.DH.15 | Oxynatromicrolite | (Na,Ca,U)2(Ta,Nb)2O6(O,F) |
| 4.DH.15 | Oxystibiomicrolite | (Sb3+,Ca)2Ta2O6O |
| 4.DH.15 | 'Hydromicrolite' | (H2O,◻)2Ta2(O,OH)6(H2O) |
| 4.DH.15 | 'Plumbomicrolite (of Hogarth 1977)' | |
| 4.DH.15 | Hydrokenomicrolite | (◻,H2O)2Ta2(O,OH)6(H2O) |
| 4.DH.15 | Hydroxykenoelsmoreite | (◻,Pb)2(W,Fe3+,Al)2(O,OH)6(OH) |
| 4.DH.15 va | 'Yttromicrolite (of Hogarth)' | (Ca,Y3+,U,Na)2-x(Ta,Nb,Ti,Fe3+)2O7 |
| 4.DH.15 | Hydroxykenopyrochlore | (◻,Ce,Ba)2(Nb,Ti)2O6(OH,F) |
| 4.DH.15 | Hydroxymanganopyrochlore | (Mn2+,Th,Na,Ca,REE)2(Nb,Ti)2O6(OH) |
| 4.DH.20 | 'Cuproroméite' | Cu2Sb2(O,OH)7 |
| 4.DH.20 | Hydroxycalcioroméite | (Ca,Sb3+)2(Sb5+,Ti)2O6(OH) |
| 4.DH.20 | Bindheimite | Pb2Sb2O6O |
| 4.DH.20 | Hydroxyferroroméite | (Fe2+1.5◻0.5)Sb5+2O6(OH) |
| 4.DH.20 | Fluorcalcioroméite | (Ca,Na,◻)2Sb5+2(O,OH)6F |
| 4.DH.20 | Oxycalcioroméite | Ca2Sb2O6O |
| 4.DH.20 | Stetefeldtite | Ag2Sb2(O,OH)7 |
| 4.DH.20 | Stibiconite | Sb3+Sb5+2O6(OH) |
| 4.DH.20 | Monimolite | Pb2Sb5+2O7 |
| 4.DH.25 | Rosiaite | PbSb5+2O6 |
| 4.DH.30 | Stefanweissite | (Ca,REE)2Zr2(Nb,Ti)(Ti,Nb)2Fe2+O14 |
| 4.DH.30 | Zirconolite | CaZrTi2O7 |
| 4.DH.30 | Laachite | (Ca,Mn)2Zr2Nb2TiFeO14 |
| 4.DH.30 | Nöggerathite-(Ce) | (Ce,Ca)2Zr2(Nb,Ti)(Ti,Nb)2Fe2+O14 |
| 4.DH.35 | Liandratite | U(Nb,Ta)2O8 |
| 4.DH.35 | Petscheckite | UFe(Nb,Ta)2O8 |
| 4.DH.40 | Ingersonite | Ca3Mn2+Sb5+4O14 |
| 4.DH.45 | Pittongite | Na0.22(W,Fe3+)(O,OH)3 · 0.44H2O |
| 4.DH.50 | Tazzoliite | Ba4-xNaxTi2Nb3SiO17[PO2(OH)2]x(OH)(1-2x) |
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 Oxycalciomicrolite
mindat.org URL:
https://www.mindat.org/min-40355.html
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References for Oxycalciomicrolite
Reference List:
Černý, Petr, Chapman, Ron, Ferreira, Karen, Smeds, Sten-Anders (2004) Geochemistry of oxide minerals of Nb, Ta, Sn, and Sb in the Varuträsk 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, Frédéric, 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 Guimarães (2020) Oxycalciomicrolite, (Ca,Na)2(Ta,Nb,Ti)2O6(O,F), a new member of the microlite group (pyrochlore supergroup) from the Paleoproterozoic São João del Rei Pegmatite Province, Minas Gerais state, Brazil. Mineralogical Magazine, 84 (6) 854-858 doi:10.1180/mgm.2020.74
Localities for Oxycalciomicrolite
Showing 12 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.
Brazil | |
| Andrade (2007) |
| Menezes da Silva et al. (2020) +1 other reference |
Italy | |
| Vignola et al. (2011) |
| Guastoni et al. (2008) +2 other references |
| Vignola et al. (2018) |
| Menezes da Silva et al. (2020) |
| Menezes da Silva et al. (2020) | |
| Menezes da Silva et al. (2020) | |
Mozambique | |
| MnhnL collection |
Sweden | |
| Černý et al. (2004) +1 other reference |
| Knut Eldjarn Collection Similar specimen from the locality in the NRM (Stockholm) |
USA | |
| Duresky et al. (2025) |
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Timmerhult, Orust, Västra Götaland County, Sweden