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About Minasgeraisite-(Y)Hide

Seal of Minas Gerais, Brazil
Purple to lavender purple
Sub-Vitreous, Resinous, Dull
6 - 7
Specific Gravity:
Crystal System:
After the type locality in the state of Minas Gerais, Brazil, plus the suffix "-(Y)" due to the dominance of yttrium in the composition.
Gadolinite-Datolite Group.

Former status: "Approved species, but validity may be questionable (Demartin et al., 2001)".

The validity was actually confirmed together with a rather strong redefinition, by Cooper & Hawthorne (2018). The authors suggest formation of a triclinic subgroup within the gadolinite-datolite group to which the minasgeraisite-(Y) now belongs.

Originally thought to be: CaBe2Y2Si2O10.

Classification of Minasgeraisite-(Y)Hide

Redefined by the IMA
Approval Year:
Approval History:
Approved IMA 1983 (IMA 1983-090)

9 : SILICATES (Germanates)
A : Nesosilicates
J : Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO4

54 : NESOSILICATES Borosilicates and Some Beryllosilicates
2 : Borosilicates and Some Beryllosilicates with B in [4] coordination

14 : Silicates not Containing Aluminum
3 : Silicates of Be

Physical Properties of Minasgeraisite-(Y)Hide

Sub-Vitreous, Resinous, Dull
Usually subvitreous, but may form dull fine-grained coatings.
Purple to lavender purple
Very pale purple
6 - 7 on Mohs scale
{100}, "a second good cleavage" also noted
4.29 g/cm3 (Measured)    4.90 g/cm3 (Calculated)
Calculated density for theoretically pure material

Optical Data of Minasgeraisite-(Y)Hide

Biaxial (+)
RI values:
nα = 1.740 nβ = 1.754 nγ = 1.786
Measured: 50° to 72°, Calculated: 68°
Max Birefringence:
δ = 0.046
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
r > v weak
Colorless to pale grayish yellow

Chemical Properties of Minasgeraisite-(Y)Hide


Crystallography of Minasgeraisite-(Y)Hide

Crystal System:
Class (H-M):
1 - Pedial
Space Group:
Cell Parameters:
a = 9.994(4) Å, b = 7.705(3) Å, c = 4.764(2) Å
α = 90.042(9)°, β = 90.218(14)°, γ = 90.034(9)°
a:b:c = 1.297 : 1 : 0.618
Unit Cell V:
366.84 ų (Calculated from Unit Cell)

X-Ray Powder DiffractionHide

Powder Diffraction Data:
5.99 Å(30)
3.71 Å(30)
3.41 Å(30)
3.11 Å(100)
2.83 Å(100)
2.54 Å(90)
2.25 Å(30)
2.19 Å(30)

Geological EnvironmentHide

Paragenetic Mode(s):

Type Occurrence of Minasgeraisite-(Y)Hide

General Appearance of Type Material:
Purple botryoidal clusters with minutely textured surface where crystal terminations meet.
Geological Setting of Type Material:
With milarite in late stage crystallization of a granite pegmatite.
Associated Minerals at Type Locality:
Foord, E. E., Gaines, R. V., Crock, .J G., Simmons, W. B., Barbosa, C. P. (1986) Minasgeraisite, a new member of the gadolinite group from Minas Gerais, Brazil. American Mineralogist 71: 603-607

Synonyms of Minasgeraisite-(Y)Hide

Relationship of Minasgeraisite-(Y) to other SpeciesHide

Other Members of this group:
Gadolinite-(Ce)(Ce,La,Nd,Y)2Fe2+Be2Si2O10Mon. 2/m
Gadolinite-(Nd)Nd2Fe2+Be2O2(SiO4)2Mon. 2/m : P21/b
Gadolinite-(Y)Y2Fe2+Be2Si2O10Mon. 2/m : P21/b
Hingganite-(Ce)(Ce,REE)2(□,Fe2+)Be2[SiO4]2(OH)2Mon. 2/m : P21/b
Hingganite-(Nd)Nd2☐Be2Si2O8(OH)2Mon. 2/m : P21/b
Hingganite-(Y)(Y,REE,Ca)2(□,Fe2+)Be2[SiO4]2(OH)2Mon. 2/m : P21/b
Hingganite-(Yb)(Yb,Y,REE)2□Be2[SiO4]2(OH)2Mon. 2/m : P21/b
Unnamed (OH-analogue of Gadolinite-(Y))(Y,Ca)2(Fe,☐)Be2Si2O8(OH,O)2Mon. 2/m

Common AssociatesHide

Associated Minerals Based on Photo Data:
1 photo of Minasgeraisite-(Y) associated with MuscoviteKAl2(AlSi3O10)(OH)2
1 photo of Minasgeraisite-(Y) associated with FluoriteCaF2

Related Minerals - Nickel-Strunz GroupingHide

9.AJ.Hingganite-(Nd)Nd2☐Be2Si2O8(OH)2Mon. 2/m : P21/b
9.AJ.Arrheniusite-(Ce)CaMg[(Ce7Y3)Ca5](SiO4)4(Si2B3AsO18)(BO3)F11Trig. 3m : R3m
9.AJ.05Grandidierite(Mg,Fe2+)(Al,Fe3+)3(SiO4)(BO3)O2Orth. mmm (2/m 2/m 2/m)
9.AJ.05Ominelite(Fe2+,Mg)(Al,Fe3+)3(SiO4)(BO3)O2Orth. mmm (2/m 2/m 2/m)
9.AJ.10Dumortierite(Al,Fe3+)7(SiO4)3(BO3)O3Orth. mmm (2/m 2/m 2/m)
9.AJ.10Holtite(Ta0.60.4)Al6BSi3O18(O,OH)2.25Orth. mmm (2/m 2/m 2/m) : Pnma
9.AJ.10Magnesiodumortierite(Mg,Ti,◻(Al,Mg)2Al4Si3O18-y(OH)yB y = 2-3Orth.
9.AJ.20BakeriteCa4(H5B5Si3O20)Mon. 2/m : P21/b
9.AJ.20DatoliteCaB(SiO4)(OH)Mon. 2/m : P21/b
9.AJ.20Gadolinite-(Ce)(Ce,La,Nd,Y)2Fe2+Be2Si2O10Mon. 2/m
9.AJ.20Gadolinite-(Y)Y2Fe2+Be2Si2O10Mon. 2/m : P21/b
9.AJ.20Hingganite-(Ce)(Ce,REE)2(□,Fe2+)Be2[SiO4]2(OH)2Mon. 2/m : P21/b
9.AJ.20Hingganite-(Y)(Y,REE,Ca)2(□,Fe2+)Be2[SiO4]2(OH)2Mon. 2/m : P21/b
9.AJ.20Hingganite-(Yb)(Yb,Y,REE)2□Be2[SiO4]2(OH)2Mon. 2/m : P21/b
9.AJ.20HomiliteCa2(Fe2+,Mg)B2Si2O10Mon. 2/m : P21/b
9.AJ.25Stillwellite-(Ce)(Ce,La,Ca)BSiO5Trig. 3 : P31
9.AJ.30Cappelenite-(Y)Ba(Y,Ce)6Si3B6O24F2Trig. 3 : P3
9.AJ.35Okanoganite-(Y)(Na,Ca)3(Y,Ce)12Si6B2O27F14Trig. 3m : R3m
9.AJ.35Hundholmenite-(Y)(Y,REE,Ca,Na)15(Al,Fe3+)(CaxAs3+1-x)(Si,As5+)Si6B3(O,F)48Trig. 3m : R3m
9.AJ.35Proshchenkoite-(Y)Ca(Y,REE,Ca,Na,Mn)15Fe2+(P,Si)Si6B3O34F14Trig. 3m : R3m
9.AJ.40JadariteLiNaSiB3O7(OH)Mon. 2/m

Related Minerals - Dana Grouping (8th Ed.)Hide

54.2.1b.1BakeriteCa4(H5B5Si3O20)Mon. 2/m : P21/b
54.2.1b.2Gadolinite-(Ce)(Ce,La,Nd,Y)2Fe2+Be2Si2O10Mon. 2/m
54.2.1b.3Gadolinite-(Y)Y2Fe2+Be2Si2O10Mon. 2/m : P21/b
54.2.1b.5HomiliteCa2(Fe2+,Mg)B2Si2O10Mon. 2/m : P21/b

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

14.3.1PhenakiteBe2SiO4Trig. 3 : R3
14.3.2BertranditeBe4(Si2O7)(OH)2Orth. mm2 : Cmc21
14.3.3BerylliteBe3(SiO4)(OH)2 · H2OOrth.
14.3.4LiberiteLi2BeSiO4Mon. m : Pm
14.3.5ChkaloviteNa2BeSi2O6Orth. mm2 : Fdd2
14.3.6EudidymiteNa2Be2Si6O15 · H2OMon. 2/m : B2/b
14.3.7EpididymiteNa2Be2Si6O15 · H2OOrth. mmm (2/m 2/m 2/m) : Pnma
14.3.10Semenovite-(Ce)Na8Ca2FeBe6Ce2Si14O40(OH)4F4Orth. mmm (2/m 2/m 2/m)
14.3.12Hingganite-(Ce)(Ce,REE)2(□,Fe2+)Be2[SiO4]2(OH)2Mon. 2/m : P21/b
14.3.13Hingganite-(Yb)(Yb,Y,REE)2□Be2[SiO4]2(OH)2Mon. 2/m : P21/b
14.3.14Hingganite-(Y)(Y,REE,Ca)2(□,Fe2+)Be2[SiO4]2(OH)2Mon. 2/m : P21/b
14.3.16SørenseniteNa4SnBe2Si6O16(OH)4Mon. 2/m : B2/b
14.3.17TrimeriteCaMn2+2Be3(SiO4)3Mon. 2/m : P21/m
14.3.18ChiavenniteCaMnBe2Si5O13(OH)2 · 2H2OMon. 2/m : P21/b
14.3.19Tvedalite(Ca,Mn)4Be3Si6O17(OH)4 · 3H2OOrth.
14.3.21SverigeiteNaMnMgSnBe2(SiO4)3(OH)Orth. mmm (2/m 2/m 2/m) : Imma
14.3.23Gadolinite-(Y)Y2Fe2+Be2Si2O10Mon. 2/m : P21/b
14.3.24Gadolinite-(Ce)(Ce,La,Nd,Y)2Fe2+Be2Si2O10Mon. 2/m

Fluorescence of Minasgeraisite-(Y)Hide

Nonfluorescent in SW or LW UV

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.

References for Minasgeraisite-(Y)Hide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Foord, E. E., Gaines, R. V., Crock, J. G., Simmons, W. B., Jr., Barbosa, C. P. (1986) Minasgeraisite, a new member of the gadolinite group from Minas Gerais, Brazil. American Mineralogist: 71: 603-607.
DeMartin, F., Pilati, T., Diella, V., Gentile, P. & Gramaccioli, C. M. (1993) A crystal-chemical investigation of Alpine gadolinite. Canadian Mineralogist: 31: 127-136.
Demartin, F., Minaglia, A. & Gramaccioli, C. M. (2001) Characterization of gadolinite-group minerals using crystallographic data only: the case of hingganite-(Y) from Cuasso al Monte, Italy. Canadian Mineralogist: 39: 1105-1114.
Cooper, M.A., Hawthorne, F.C. (2018) Cation order in the crystal structure of ‘minasgeraisite-(Y)’: Dedicated to our friend the late Luis Menezes, who brought this mineral to our attention and graciously provided a superior specimen with crystals suitable for single-crystal structure work. Mineralogical Magazine: 82(2): 301-312.

Internet Links for Minasgeraisite-(Y)Hide

Localities for Minasgeraisite-(Y)Hide

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.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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 (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Brazil (TL)
  • Minas Gerais
    • Jaguaraçu
Foord, E. E., Gaines, R. V., Crock, J. G., Simmons, W. B., Jr., Barbosa, C. P. (1986): Minasgeraisite, a new member of the gadolinite group from Minas Gerais, Brazil. American Mineralogist 71, 603-607.; Mineralogical Record - Vol. 25, No. 3
BROSSEAU-LIARD, A. (2012) The nature and origin of REE and associated rare metal mineralization in the
Czech Republic
  • Central Bohemian Region
    • Kutná Hora District
      • Zruč nad Sázavou
Kadlec T.: Nové minerály ve Vlastějovicích. Minerál, 2010, 18, 3, 216-220.
          • Moldanubian Zone pegmatites
            • Holý vrch deposit
Novak, M., Kadlec, T., & Gadas, P. (2013). Geological position, mineral assemblages and contamination of granitic pegmatites in the Moldanubian Zone, Czech Republic; examples from the Vlastejovice region. Journal of Geosciences, 58(1), 21-47.
  • Bavaria
    • Lower Bavaria
      • Passau District
        • Tittling
          • Matzersdorf
Habel, A. & M. (2009): Minasgeraisit-(Y) aus dem Krennbruch in Matzersdorf/Tittling. Mineralien-Welt 20 (5), 51-53.
  • Saxony
    • Görlitz District
      • Thiemendorf
WITZKE, T. & GIESLER, T. (2014): Beryllium-Mineralien aus dem Königshainer Granit.- Mineralien-Welt 25(2), 96-103
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