Minasgeraisite-(Y)
A discredited species name
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About Minasgeraisite-(Y)
Seal of Minas Gerais, Brazil
Formula:
(Ca2Y2)◻2(Be2B2)[SiO4]4(OH)4
Colour:
Purple to lavender purple
Lustre:
Sub-Vitreous, Resinous, Dull
Hardness:
6 - 7
Specific Gravity:
4.29
Crystal System:
Triclinic
Member of:
Name:
After the type locality in the state of Minas Gerais, Brazil, plus the suffix "-(Y)" due to the dominance of yttrium in the composition.
First Recorded Locality:
Discredited (2023): finally proved to be an ordered intermediate, between datolite and hingganite-(Y).
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.
The Bi-richest portions represent an intermediate member between datolite, hingganite-(Y) and a hypothetical end-member formulated as Bi2◻Be2Si2O8(OH)2.
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.
The Bi-richest portions represent an intermediate member between datolite, hingganite-(Y) and a hypothetical end-member formulated as Bi2◻Be2Si2O8(OH)2.
Unique Identifiers
Mindat ID:
2716
Long-form identifier:
mindat:1:1:2716:4
IMA Classification of Minasgeraisite-(Y)
Discredited
IMA Formula:
CaBe2Y2Si2O10
Approval year:
1983
Approval history:
Approved IMA 1983 (IMA 1983-090)
Discreditation: Atencio, D. (2023): Proposal 23-F
Discreditation: Atencio, D. (2023): Proposal 23-F
Classification of Minasgeraisite-(Y)
9.AJ.20
9 : SILICATES (Germanates)
A : Nesosilicates
J : Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO4
9 : SILICATES (Germanates)
A : Nesosilicates
J : Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO4
54.2.1b.6
54 : NESOSILICATES Borosilicates and Some Beryllosilicates
2 : Borosilicates and Some Beryllosilicates with B in [4] coordination
54 : NESOSILICATES Borosilicates and Some Beryllosilicates
2 : Borosilicates and Some Beryllosilicates with B in [4] coordination
14.3.15
14 : Silicates not Containing Aluminum
3 : Silicates of Be
14 : Silicates not Containing Aluminum
3 : Silicates of Be
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 |
|---|---|---|
| Mgr-Y | 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 Minasgeraisite-(Y)
Sub-Vitreous, Resinous, Dull
Transparency:
Transparent
Comment:
Usually subvitreous, but may form dull fine-grained coatings.
Colour:
Purple to lavender purple
Streak:
Very pale purple
Hardness:
6 - 7 on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
{100}, "a second good cleavage" also noted
{100}, "a second good cleavage" also noted
Fracture:
Irregular/Uneven
Density:
4.29 g/cm3 (Measured) 4.90 g/cm3 (Calculated)
Comment:
Calculated density for theoretically pure material
Optical Data of Minasgeraisite-(Y)
Type:
Biaxial (+)
RI values:
nα = 1.740 nβ = 1.754 nγ = 1.786
2V:
Measured: 50° to 72°, Calculated: 68°
Birefringence:
0.046
Max. Birefringence:
δ = 0.046
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars.
Surface Relief:
Moderate
Dispersion:
r > v weak
Comments:
Colorless to pale grayish yellow
Chemistry of Minasgeraisite-(Y)
Mindat Formula:
(Ca2Y2)◻2(Be2B2)[SiO4]4(OH)4
Element Weights:
Crystallography of Minasgeraisite-(Y)
Crystal System:
Triclinic
Class (H-M):
1 - Pedial
Space Group:
P1
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)°
α = 90.042(9)°, β = 90.218(14)°, γ = 90.034(9)°
Ratio:
a:b:c = 1.297 : 1 : 0.618
Unit Cell V:
366.84 ų (Calculated from Unit Cell)
Z:
2
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 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) |
Comments:
39-344
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
First Recorded Occurrence of Minasgeraisite-(Y)
General Appearance of First Recorded Material:
Purple botryoidal clusters with minutely textured surface where crystal terminations meet.
Geological Setting of First Recorded Material:
With milarite in late stage crystallization of a granite pegmatite.
Associated Minerals at First Recorded Locality:
Synonyms of Minasgeraisite-(Y)
Relationship of Minasgeraisite-(Y) to other Species
Member of:
Other Members of Gadolinite Subgroup:
| 'Calcybeborosilite-(Y)' | (Y,Ca)2(◻,Fe2+)(B,Be)2[SiO4]2(OH,O)2 | Mon. |
| Hingganite-(Ce) | (Ce,REE)2(◻,Fe2+)Be2[SiO4]2(OH)2 | Mon. 2/m : P21/b |
| Hingganite-(Nd) | Nd2◻Be2Si2O8(OH)2 | Mon. 2/m : P21/b |
| Hingganite-(Y) | (Y,REE,Ca)2(◻,Fe2+)Be2[SiO4]2(OH)2 | Mon. 2/m : P21/b |
| Hingganite-(Yb) | (Yb,Y,REE)2◻Be2[SiO4]2(OH)2 | Mon. 2/m : P21/b |
| 'Unnamed (OH-analogue of Gadolinite-(Y))' | (Y,Ca)2(Fe,◻)Be2Si2O8(OH,O)2 | Mon. 2/m |
Common Associates
Associations Based on Photo Data:
| 11 photos of Minasgeraisite-(Y) associated with Muscovite | KAl2(AlSi3O10)(OH)2 |
| 3 photos of Minasgeraisite-(Y) associated with Milarite | K(◻H2O)Ca2(Be2Al)[Si12O30] |
| 2 photos of Minasgeraisite-(Y) associated with Chernovite-(Y) | Y(AsO4) |
| 2 photos of Minasgeraisite-(Y) associated with Microcline | K(AlSi3O8) |
| 1 photo of Minasgeraisite-(Y) associated with Hingganite-(Y) | (Y,REE,Ca)2(◻,Fe2+)Be2[SiO4]2(OH)2 |
| 1 photo of Minasgeraisite-(Y) associated with Fluorite | CaF2 |
Related Minerals - Strunz-mindat Grouping
| 9.AJ. | Hingganite-(Nd) | Nd2◻Be2Si2O8(OH)2 |
| 9.AJ. | Arrheniusite-(Ce) | CaMg[(Ce7Y3)Ca5](SiO4)4(Si2B3AsO18)(BO3)F11 |
| 9.AJ.05 | Ominelite | (Fe2+,Mg)(Al,Fe3+)3(SiO4)(BO3)O2 |
| 9.AJ.05 | Grandidierite | (Mg,Fe2+)(Al,Fe3+)3(SiO4)(BO3)O2 |
| 9.AJ.10 | Dumortierite | Al(Al2O)(Al2O)2(SiO4)3(BO3) |
| 9.AJ.10 | Nioboholtite | (Nb0.6◻0.4)Al6BSi3O18 |
| 9.AJ.10 | Titanoholtite | (Ti0.75◻0.25)Al6BSi3O18 |
| 9.AJ.10 | Holtite | (Ta0.6◻0.4)Al6BSi3O18(O,OH)2.25 |
| 9.AJ.10 | Magnesiodumortierite | Mg(Al2OH)(Al2O)2(SiO4)3(BO3) |
| 9.AJ.15 | Garrelsite | Ba3NaSi2B7O16(OH)4 |
| 9.AJ.20 | 'Muromontite' | near Be2FeY2Si3O12 |
| 9.AJ.20 | Gadolinite-(Nd) | Nd2Fe2+Be2O2(SiO4)2 |
| 9.AJ.20 | Datolite | CaB(SiO4)(OH) |
| 9.AJ.20 | Melanocerite-(Ce) | (Ce,Ca)5(SiO4,BO4)3(OH,O) |
| 9.AJ.20 | Gadolinite-(Ce) | (Ce,La,Nd,Y)2Fe2+Be2Si2O10 |
| 9.AJ.20 | Gadolinite-(Y) | Y2Fe2+Be2Si2O10 |
| 9.AJ.20 | 'Unnamed (OH-analogue of Gadolinite-(Y))' | (Y,Ca)2(Fe,◻)Be2Si2O8(OH,O)2 |
| 9.AJ.20 | Hingganite-(Ce) | (Ce,REE)2(◻,Fe2+)Be2[SiO4]2(OH)2 |
| 9.AJ.20 | Hingganite-(Y) | (Y,REE,Ca)2(◻,Fe2+)Be2[SiO4]2(OH)2 |
| 9.AJ.20 | Hingganite-(Yb) | (Yb,Y,REE)2◻Be2[SiO4]2(OH)2 |
| 9.AJ.20 | Homilite | Ca2(Fe2+,Mg)B2Si2O10 |
| 9.AJ.20 | 'Calcybeborosilite-(Y)' | (Y,Ca)2(◻,Fe2+)(B,Be)2[SiO4]2(OH,O)2 |
| 9.AJ.25 | Stillwellite-(La) | LaBSiO5 |
| 9.AJ.25 | Stillwellite-(Ce) | (Ce,La,Ca)BSiO5 |
| 9.AJ.30 | Cappelenite-(Y) | Ba(Y,Ce)6Si3B6O24F2 |
| 9.AJ.35 | Laptevite-(Ce) | Ca6(Fe2+,Mn2+)Y3REE7(SiO4)3(PO4)(B3Si3O18)(BO3)F11 |
| 9.AJ.35 | Proshchenkoite-(Y) | Ca(Y,REE,Ca,Na,Mn)15Fe2+(P,Si)Si6B3O34F14 |
| 9.AJ.35 | Okanoganite-(Y) | (Na,Ca)3(Y,Ce)12Si6B2O27F14 |
| 9.AJ.35 | Hundholmenite-(Y) | (Y,REE,Ca,Na)15(Al,Fe3+)(CaxAs3+1-x)(Si,As5+)Si6B3(O,F)48 |
| 9.AJ.35 | Vicanite-(Ce) | (Ca,Ce,La,Th)15As5+(As3+0.5,Na0.5)Fe3+Si6B4O40F7 |
| 9.AJ.40 | Jadarite | LiNaSiB3O7(OH) |
Fluorescence of Minasgeraisite-(Y)
Nonfluorescent in SW or LW UV.
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 Minasgeraisite-(Y)
mindat.org URL:
https://www.mindat.org/min-2716.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Minasgeraisite-(Y)
Reference List:
Foord, E. E., Gaines, R. V., Crock, J. G., Simmons, W. B., Barbosa, C. P. Jr. (1986) Minasgeraisite, a new member of the gadolinite group from Minas Gerais, Brazil. American Mineralogist, 71 (3-4) 603-607
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. The Canadian Mineralogist, 39 (4). 1105-1114 doi:10.2113/gscanmin.39.4.1105
Bačík, Peter, Miyawaki, Ritsuro, Atencio, Daniel, Cámara, Fernando, Fridrichová, Jana (2017) Nomenclature of the gadolinite supergroup. European Journal of Mineralogy, 29 (6) 1067-1082 doi:10.1127/ejm/2017/0029-2659
Cooper, Mark A., Hawthorne, Frank C. (2018) Cation order in the crystal structure of ‘minasgeraisite-(Y)’. Mineralogical Magazine, 82 (2). doi:10.1180/minmag.2017.081.043
Vereshchagin, Oleg S., Gorelova, Liudmila A., Shagova, Anastasia K., Kasatkin, Anatoly V., Škoda, Radek, Bocharov, Vladimir N., Vlasenko, Natalia S., Vašinová Galiová, Michaela (2023) Re-investigation of ‘minasgeraisite-(Y)’ from the Jaguaraçu pegmatite, Brazil and high-temperature crystal chemistry of gadolinite-supergroup minerals. Mineralogical Magazine, 87 (3) 470-479 doi:10.1180/mgm.2023.19
Localities for Minasgeraisite-(Y)
Showing 7 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 (FRL) | |
| Foord et al. (1986) +1 other reference |
Canada | |
| BROSSEAU-LIARD (2012) | |
Czech Republic | |
| Kadlec T.: Nové minerály ve ... |
| Novák et al. (2013) +1 other reference |
Germany | |
| Habel (2009) |
| Witzke et al. (2014) |
Hungary | |
| Zajzon et al. (2015) |
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Jaguaraçu pegmatite, Jaguaraçu, Minas Gerais, Brazil