Microlite Group
A group of related mineral species
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About Microlite Group
Formula:
A2-mTa2X6-wZ-n
The A site, therefore, may host Na, Ca, Sr, Pb2+, Sn2+, Sb3+, Y, U, □, or H2O or, less frequently Ag, Mn, Ba, Fe2+, Bi3+, Ce (and other REE), Sc or Th.
X typically is O but can include subordinate OH and F.
Z typically is an anion, but can also be a vacancy, H2O, or a very large (>> 1.0 Å) monovalent cation (site 8b). Examples are OH–, F, O, □, H2O, K, Cs, Rb.
The symbols m, w, and n represent parameters that indicate incomplete occupancy of the A, X and Z sites, respectively. (Atencio et al. 2010).
X typically is O but can include subordinate OH and F.
Z typically is an anion, but can also be a vacancy, H2O, or a very large (>> 1.0 Å) monovalent cation (site 8b). Examples are OH–, F, O, □, H2O, K, Cs, Rb.
The symbols m, w, and n represent parameters that indicate incomplete occupancy of the A, X and Z sites, respectively. (Atencio et al. 2010).
Colour:
Pale yellow to reddish brown, sometimes emerald-green
Lustre:
Vitreous, Resinous
Hardness:
5 - 5½
Specific Gravity:
5.9 - 6.4
Crystal System:
Isometric
Member of:
Name:
The microlite group has its name after the generic name microlite which was first introduced in 1835 by C.U. Shepard. From the Greek μικρός, small, in allusion to the usually small size of the crystals from the first recorded locality.
First Recorded Locality:
Ta-dominant members of the Pyrochlore Supergroup.
The nomenclature was recently revised by Atencio et al. (2010); see also Christy & Atencio (2013).
The nomenclature was recently revised by Atencio et al. (2010); see also Christy & Atencio (2013).
Visit gemdat.org for gemological information about Microlite Group.
Unique Identifiers
Mindat ID:
2705
Long-form identifier:
mindat:1:1:2705:8
GUID
(UUID V4):
(UUID V4):
b4325b6b-4b46-41b0-96fd-1d69457cbb9b
IMA Classification of Microlite Group
IMA status notes:
IMA Approved Group Name, Renamed by the IMA
IMA Formula:
(Ca,Na)2Ta2(O,OH,F)7
Approval history:
Renamed by IMA: 2010
Classification of Microlite Group
4.00.
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
0 :
0 :
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
0 :
0 :
8.2.2.1
8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
2 : A2B2O6(O,OH,F)
8 : MULTIPLE OXIDES CONTAINING NIOBIUM,TANTALUM OR TITANIUM
2 : A2B2O6(O,OH,F)
18.1.11
18 : Niobates and Tantalates
1 : Niobates and tantalates containing neither rare earths nor U
18 : Niobates and Tantalates
1 : Niobates and tantalates containing neither rare earths nor U
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 |
---|---|---|
Mic | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Mie | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Microlite Group
Vitreous, Resinous
Transparency:
Transparent
Colour:
Pale yellow to reddish brown, sometimes emerald-green
Streak:
Light yellow, brownish
Hardness:
5 - 5½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Imperfect/Fair
Octahedral{111} (may be a parting), sometimes distinct, but usually not distinguishable.
Octahedral{111} (may be a parting), sometimes distinct, but usually not distinguishable.
Fracture:
Irregular/Uneven, Splintery, Sub-Conchoidal
Density:
5.9 - 6.4 g/cm3 (Measured) 6.33 g/cm3 (Calculated)
Comment:
Calc for Ca:Na = 1:1
Optical Data of Microlite Group
Type:
Isotropic
Chemistry of Microlite Group
Mindat Formula:
A2-mTa2X6-wZ-n
The A site, therefore, may host Na, Ca, Sr, Pb2+, Sn2+, Sb3+, Y, U, □, or H2O or, less frequently Ag, Mn, Ba, Fe2+, Bi3+, Ce (and other REE), Sc or Th.
X typically is O but can include subordinate OH and F.
Z typically is an anion, but can also be a vacancy, H2O, or a very large (>> 1.0 Å) monovalent cation (site 8b). Examples are OH–, F, O, □, H2O, K, Cs, Rb.
The symbols m, w, and n represent parameters that indicate incomplete occupancy of the A, X and Z sites, respectively. (Atencio et al. 2010).
The A site, therefore, may host Na, Ca, Sr, Pb2+, Sn2+, Sb3+, Y, U, □, or H2O or, less frequently Ag, Mn, Ba, Fe2+, Bi3+, Ce (and other REE), Sc or Th.
X typically is O but can include subordinate OH and F.
Z typically is an anion, but can also be a vacancy, H2O, or a very large (>> 1.0 Å) monovalent cation (site 8b). Examples are OH–, F, O, □, H2O, K, Cs, Rb.
The symbols m, w, and n represent parameters that indicate incomplete occupancy of the A, X and Z sites, respectively. (Atencio et al. 2010).
Crystallography of Microlite Group
Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
Fd3m
Morphology:
Octahedral, often with subordinate {001}, {113} or {001}.
Twinning:
Twin plane {111} (spinel law twins), rare.
Crystallographic forms of Microlite Group
Crystal Atlas:
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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) |
---|---|---|---|---|---|---|---|
0018462 | Fluornatromicrolite | Andrade M B, Atencio D, Menezes L A D, Ellena J (2011) The crystal structure of a microlite-group mineral with a formula near NaCaTa2O6F from the Morro Redondo mine, Coronel Murta, Minas Gerias, Brazil The Canadian Mineralogist 49 615-621 | 2011 | Morro Redondo mine, Coronel Murta, Minas Gerias, Brazil | 0 | 293 | |
0018616 | Fluornatromicrolite | Witzke T, Steins M, Doering T, Schuckmann W, Wegner R, Pollmann H (2011) Fluornatromicrolite, (Na,Ca,Bi)2Ta2O6F, a new mineral species from Quixaba, Paraiba, Brazil The Canadian Mineralogist 49 1105-1110 | 2011 | Quixaba, Paraiba, Brazil | 0 | 293 | |
0019993 | Fluorcalciomicrolite | Andrade M B, Atencio D, Persiano A I C, Ellena J (2013) Fluorcalciomicrolite, (Ca,Na,_)2Ta2O6F, a new microlite-group mineral from Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil Mineralogical Magazine 77 2989-2996 | 2013 | Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil | 0 | 293 | |
0012114 | Oxystannomicrolite | Gasperin M (1960) Contribution a l'etude de quelques oxydes doubles que forme le tantale avec l'etain, l'uranium et le calcium. _cod_database_code 1001840 Bulletin de la Societe Francaise de Mineralogie et de Cristallographie 83 1-21 | 1960 | 0 | 293 | ||
0012249 | Oxystannomicrolite | Gasperin M (1955) Synthese et identification de deux oxydes doubles de tantale et d'etain Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences 240 2340-2342 | 1955 | 0 | 293 | ||
0014636 | Hydroxykenomicrolite | Ercit T S, Cerny P, Hawthorne F C (1993) Cesstibtantite - a geologic introduction to the inverse pyrochlores Mineralogy and Petrology 48 235-255 | 1993 | Leshaia pegmatite, Kola Peninsula, Russia | 0 | 293 | |
0014637 | Hydroxykenomicrolite | Ercit T S, Cerny P, Hawthorne F C (1993) Cesstibtantite - a geologic introduction to the inverse pyrochlores Loclity: Tanco pegmatite, Manitoba, Canada Mineralogy and Petrology 48 235-255 | 1993 | 0 | 293 | ||
0019783 | Hydrokenomicrolite | Andrade M B, Atencio D, Chukanov N V, Ellena J (2013) Hydrokenomicrolite, ([_],H2O)2Ta2(O,OH)6(H2O), a new microlite-group mineral from Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil American Mineralogist 98 292-296 | 2013 | Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil | 0 | 293 |
CIF Raw Data - click here to close
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Radiation - Copper Kα
Data courtesy of RRUFF project at University of Arizona, used with permission.
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
Stage 4b: Highly evolved igneous rocks | >3.0 |
34 : Complex granite pegmatites |
Geological Setting:
Albitized parts of granite pegmatites.
First Recorded Occurrence of Microlite Group
Synonyms of Microlite Group
Other Language Names for Microlite Group
Varieties of Microlite Group
Bariomicrolite (of Hogarth 1977) | A discredited mineral. According to the new IMA nomenclature of the Pyrochlore Supergroup the mineral formerly named as bariomicrolite is probably a hydrokenomicrolite. (Atencio et al. 2010). The type sample apparently has □ dominant at the A position ... |
Natrobistantite | Natrobistantite studied by Voloshin et al. (1983) and by Beurlen et al. (2005) are both a zero valent dominant member of the microlite group with significant contents (in wt.%) of bismuth and cesium. According to modern microprobe data at least part of N... |
Scandium Microlite (of Bergstøl & Juve) | A Sc-bearing microlite group mineral. An incompletely described mineral. "Sc exceeds 20 % of the total A atoms and is the most abundant A atom other than Ca" (Bergstøl & Juve 1988). Found in an altered area of an ixiolite. |
Stannomicrolite (of Hogarth 1977) | The stannomicrolite species of Ercit et al. (1987) [“sukulaite” of Vorma & Siivola (1967)] is oxystannomicrolite. The stannomicrolite of Uher et al. (2008) is a calciomicrolite or a zero valent dominant member of the microlite group. |
Zero valent dominant member of the Microlite Group | Where either vacancy or H2O are dominant, but it cannot be proven which one. |
Relationship of Microlite Group to other Species
Member of:
Other Members of this group:
Betafite Group | A2(Ti,Nb)2O6Z | |
Coulsellite Group | A2-mMg2F6-wF1-n | |
Elsmoreite Group | W-dominant members of the Pyrochlore Supergroup. | |
Pyrochlore Group | A2Nb2(O,OH)6Z | |
Ralstonite Group | Group, where M3+ cations are dominant at the B site, and Al is dominant among them, and F1– is ... | |
Roméite Group | A2(Sb5+)2O6Z |
Group Members:
Fluorcalciomicrolite | (Ca,Na)2(Ta,Nb)2O6F | Iso. m3m (4/m 3 2/m) : Fd3m |
Fluornatromicrolite | (Na1.5Bi0.5)Ta2O6F | Iso. m3m (4/m 3 2/m) : Fd3m |
Hydrokenomicrolite | (◻,H2O)2Ta2(O,OH)6(H2O) | Iso. m3m (4/m 3 2/m) |
Hydromicrolite | (H2O,◻)2Ta2(O,OH)6(H2O) | |
Hydroxycalciomicrolite | Ca1.5Ta2O6(OH) | Iso. 4 3 2 : P42 3 2 |
Hydroxykenomicrolite | (◻,Na,Sb3+)2Ta2O6(OH) | Iso. m3m (4/m 3 2/m) : Fd3m |
Hydroxynatromicrolite | (Na,Bi3+,◻)2Ta2O6(OH) | Iso. m3m (4/m 3 2/m) : Fd3m |
Kenoplumbomicrolite | (Pb,◻)2Ta2O6(◻,OH,O) | Iso. |
Oxybismutomicrolite | (Bi1.33◻0.67)Σ2Ta2O6O | Iso. m3m (4/m 3 2/m) : Fd3m |
Oxycalciomicrolite | Ca2Ta2O6O | Iso. m3m (4/m 3 2/m) : Fd3m |
Oxystannomicrolite | Sn2Ta2O6O | Iso. m3m (4/m 3 2/m) : Fd3m |
Oxystibiomicrolite | (Sb3+,Ca)2Ta2O6O | Iso. m3m (4/m 3 2/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/m 3 2/m) : Fd3m |
Related Minerals - Strunz-mindat Grouping
4.00. | Goethite | α-Fe3+O(OH) |
4.00. | Ferrotaaffeite-6N'3S | (Be,Zn,Mg)FeAl4O8 |
4.00. | Pyrochlore Group | A2Nb2(O,OH)6Z |
4.00. | Písekite-(Y) | (Y,As,Ca,Fe,U)(Nb,Ti,Ta)O4 |
4.00. | UM2004-19-O:AlCeGdZr | (Gd,Ce)4Al2Zr4O17 |
4.00. | UM2004-21-O:CaFeGdZr | Ca2Gd4Fe5ZrO15 |
4.00. | UM2004-27-O:GdTi | Gd2Ti4O11 |
4.00. | Mapiquiroite | (Sr,Pb)(U,Y)Fe2(Ti,Fe3+,Cr3+)18O38 |
4.00. | Almeidaite | PbZn2(Mn,Y)(Ti,Fe3+)18O37(OH,O) |
4.00. | Vapnikite | Ca2CaUO6 |
Other Information
Health Risks:
May be radioactive
Internet Links for Microlite Group
mindat.org URL:
https://www.mindat.org/min-2705.html
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References for Microlite Group
Localities for Microlite Group
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).
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.
All localities listed without proper references should be considered as questionable.
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Ipê mine, Golconda mining district, Governador Valadares, Minas Gerais, Brazil