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Minasgeraisite-(Y)

Big Photo

Jaguaraçu pegmatite (José Miranda mine; José Pinto mine; Carneirinho mine), Jaguaraçu, Minas Gerais, Southeast Region, Brazil
© Van King

Formula:
Y
 
2
CaBe
 
2
[O|SiO
 
4
]
 
2
System:MonoclinicColour:Purple to lavender purple
Lustre:Sub-Vitreous, Resinous, DullHardness:6 - 7
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. Named by Eugene Foord, Richard Gaines, J. Crock, William Simmons, and Carlos Barbosa in 1986.
Isostructural with:Gadolinite-Datolite Group


Approved species, but validity may be questionable.

Purple botryoidal clusters with minutely textured surface where crystal terminations meet.

Classification of Minasgeraisite-(Y)

IMA status:Approved 1983
Strunz 8th edition ID:8/B.29-40
Nickel-Strunz 10th (pending) edition ID:9.AJ.20

9 : SILICATES (Germanates)
A : Nesosilicates
J : Nesosilicates with BO3 triangles and/or B[4], Be[4] tetrahedra, cornersharing with SiO4
Dana 8th edition ID:54.2.1b.6

54 : NESOSILICATES Borosilicates and Some Beryllosilicates
2 : Borosilicates and Some Beryllosilicates with B in [4] coordination
Hey's CIM Ref.:14.3.15

14 : Silicates not Containing Aluminum
3 : Silicates of Be
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Type Occurrence of Minasgeraisite-(Y)

Type Locality:Jaguaraçu pegmatite (José Miranda mine; José Pinto mine; Carneirinho mine), Jaguaraçu, Minas Gerais, Southeast Region, Brazil
Year of Discovery:1986
Geological Setting of type material:With milarite in late stage crystallization of a granite pegmatite.
Associated Minerals at type locality:
QuartzMuscoviteMilariteAlbite

Physical Properties of Minasgeraisite-(Y)

Lustre:Sub-Vitreous, Resinous, Dull
Diaphaneity (Transparency):Transparent
Comment:Usually subvitreous, but may form dull fine-grained coatings.
Colour:Purple to lavender purple
Streak:Very pale purple
Hardness (Mohs):6 - 7
Tenacity:Brittle
Cleavage:Perfect
{100}, "a second good cleavage" also noted
Fracture:Irregular/Uneven
Density (measured):4.29 g/cm3
Density (calculated):4.90 g/cm3
Comment:Calculated density for theoretically pure material

Crystallography of Minasgeraisite-(Y)

Crystal System:Monoclinic
Class (H-M):2/m - Prismatic
Space Group:P21/b {P1 1 21/b} {P21/c} {P1 21/c 1} {P21/a}
Cell Parameters:a = 9.833Å, b = 7.562Å, c = 4.702Å
β = 90.46°
Ratio:a:b:c = 1.3 : 1 : 0.622
Unit Cell Volume:V 349.62 ų (Calculated from Unit Cell)
Z:2
X-Ray Powder Diffraction:
d-spacingIntensity
5.99 (30)
3.71 (30)
3.41 (30)
3.11 (100)
2.83 (100)
2.54 (90)
2.25 (30)
Comments:39-344

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
Maximum Birefringence:δ = 0.046

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:High
Dispersion:r > v weak
Comments:Colorless to pale grayish yellow

Chemical Properties of Minasgeraisite-(Y)

Formula:
Y
 
2
CaBe
 
2
[O|SiO
 
4
]
 
2
Essential elements:Be, Ca, O, Si, Y
All elements listed in formula:Be, Ca, O, Si, Y

Relationship of Minasgeraisite-(Y) to other Species

Member of Group:
Gadolinite-Datolite Group:
Related Minerals - Nickel-Strunz Grouping):

- +
9.AJ.05Grandidierite
(Mg,Fe
2+
 
)(Al,Fe
3+
 
)
 
3
[O
 
2
|BO
 
3
|SiO
 
4
]
9.AJ.05Ominelite
(Fe
2+
 
,Mg)(Al,Fe
3+
 
)
 
3
[O
 
2
|BO
 
3
|SiO
 
4
]
9.AJ.10Dumortierite
(Al,Fe
3+
 
)
 
7
[O
 
3
|BO
 
3
|(SiO
 
4
)
 
3
]
9.AJ.10Holtite
(Ta,Sb)Al
 
6
[O
 
3
|BO
 
3
|(SiO
 
4
)
 
3
]
9.AJ.10Magnesiodumortierite
(Mg,Ti,[](Al,Mg)
 
2
Al
 
4
Si
 
3
O
 
18-y
(OH)
 
y
B y = 2-3
9.AJ.15Garrelsite
Ba
 
3
NaSi
 
2
B
 
7
O
 
16
(OH)
 
4
9.AJ.20Bakerite
Ca
 
4
B
 
4
[(OH)
 
4
|HBO
 
4
|(SiO
 
4
)
 
3
]
9.AJ.20Datolite
CaB[OH|SiO
 
4
]
9.AJ.20Gadolinite-(Ce)
(Ce,La,Nd,Y)
 
2
Fe
2+
 
Be
 
2
[O|SiO
 
4
]
 
2
9.AJ.20Gadolinite-(Y)
Y
 
2
Fe
2+
 
Be
 
2
[O|SiO
 
4
]
 
2
9.AJ.20Hingganite-(Ce)
(Ce,REE)
 
2
(□,Fe
2+
 
)Be
 
2
[SiO
 
4
]
 
2
(OH)
 
2
9.AJ.20Hingganite-(Y)
(Y,REE,Ca)
 
2
(□,Fe
2+
 
)Be
 
2
[SiO
 
4
]
 
2
(OH)
 
2
9.AJ.20Hingganite-(Yb)
(Yb,Y,REE)
 
2
□Be
 
2
[SiO
 
4
]
 
2
(OH)
 
2
9.AJ.20Homilite
Ca
 
2
(Fe
2+
 
,Mg)B
 
2
[O|SiO
 
4
]
 
2
9.AJ.20Melanocerite-(Ce)
(Ce,Ca)
 
5
(Si,B)
 
3
O
 
12
(OH,F)·nH
 
2
O
9.AJ.20Calcybeborosilite-(Y)
(Y,Ca)
 
2
(□,Fe
2+
 
)(B,Be)
 
2
[SiO
 
4
]
 
2
(OH,O)
 
2
9.AJ.25Stillwellite-(Ce)
(Ce,La,Ca)BSiO
 
5
9.AJ.30Cappelenite-(Y)
Ba(Y,Ce)
 
6
Si
 
3
B
 
6
O
 
24
F
 
2
9.AJ.35Okanoganite-(Y)
(Na,Ca)
 
3
(Y,Ce)
 
12
Si
 
6
B
 
2
O
 
27
F
 
14
9.AJ.35Vicanite-(Ce)
(Ca,Ce,La,Th)
 
15
As
5+
 
(As
3+
0.5
,Na
 
0.5
)Fe
3+
 
Si
 
6
B
 
4
O
 
40
F
 
7
9.AJ.35Hundholmenite-(Y)
(Y,REE,Ca,Na)
 
15
(Al,Fe
3+
 
)(Ca
 
x
As
3+
1-x
)(Si,As
5+
 
)Si
 
6
B
 
3
(O,F)
 
48
9.AJ.35Proshchenkoite-(Y)
(Y,REE,Ca,Na,Mn)
 
15
Fe
2+
 
Ca(P,Si)Si
 
6
B
 
3
O
 
34
F
 
14
9.AJ.40Jadarite
LiNaSiB
 
3
O
 
7
(OH)
Related Minerals - Hey's Index Grouping:

- +
14.3.1Phenakite
Be
 
2
[SiO
 
4
]
14.3.2Bertrandite
Be
 
4
[(OH)
 
2
|Si
 
2
O
 
7
]
14.3.3Beryllite
Be
 
3
[(OH)
 
2
|SiO
 
4
] · H
 
2
O
14.3.4Liberite
Li
 
2
Be[SiO
 
4
]
14.3.5Chkalovite
Na
 
2
BeSi
 
2
O
 
6
14.3.6Eudidymite
Na
 
2
Be
 
2
Si
 
6
O
 
15
·H
 
2
O
14.3.7Epididymite
Na
 
2
Be
 
2
Si
 
6
O
 
15
·H
 
2
O
14.3.8Gugiaite
Ca
 
2
Be[Si
 
2
O
 
7
]
14.3.9Jeffreyite
(Ca,Na)
 
2
(Be,Al)[Si
 
2
O
 
6
(O,OH)]
14.3.10Semenovite-(Ce)
Na
 
8
Ca
 
2
FeBe
 
6
Ce
 
2
Si
 
14
O
 
40
(OH)
 
4
F
 
4
14.3.11Barylite
BaBe
 
2
[Si
 
2
O
 
7
]
14.3.12Hingganite-(Ce)
(Ce,REE)
 
2
(□,Fe
2+
 
)Be
 
2
[SiO
 
4
]
 
2
(OH)
 
2
14.3.13Hingganite-(Yb)
(Yb,Y,REE)
 
2
□Be
 
2
[SiO
 
4
]
 
2
(OH)
 
2
14.3.14Hingganite-(Y)
(Y,REE,Ca)
 
2
(□,Fe
2+
 
)Be
 
2
[SiO
 
4
]
 
2
(OH)
 
2
14.3.16Sørensenite
Na
 
4
SnBe
 
2
Si
 
6
O
 
16
(OH)
 
4
14.3.17Trimerite
CaMn
2+
2
Be
 
3
[SiO
 
4
]
 
3
14.3.18Chiavennite
CaMnBe
 
2
Si
 
5
O
 
13
(OH)
 
2
·2H
 
2
O
14.3.19Tvedalite
(Ca,Mn)
 
4
Be
 
3
Si
 
6
O
 
17
(OH)
 
4
·3H
 
2
O
14.3.20Harstigite
Ca
 
6
(Mn,Mg)Be
 
4
Si
 
6
(O,OH)
 
24
14.3.21Sverigeite
NaMnMgSnBe
 
2
Si
 
3
O
 
12
(OH)
14.3.22Joesmithite
PbCa
 
2
Mg
 
3
Fe
3+
2
[Si
 
6
Be
 
2
O
 
22
](OH)
 
2
14.3.23Gadolinite-(Y)
Y
 
2
Fe
2+
 
Be
 
2
[O|SiO
 
4
]
 
2
14.3.24Gadolinite-(Ce)
(Ce,La,Nd,Y)
 
2
Fe
2+
 
Be
 
2
[O|SiO
 
4
]
 
2
14.3.25Calciogadolinite-(Y)
(YCa)
 
2
Fe
3+
 
Be
 
2
[SiO
 
4
]
 
2
(OH)
 
2

Other Names for Minasgeraisite-(Y)

Synonyms:
IMA1983-090
Other Languages:

Other Information

Fluorescence in UV light:Nonfluorescent in SW or LW UV
Health Warning: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)

Reference List:American Mineralogist (1986): 71: 603-607.

Internet Links for Minasgeraisite-(Y)

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    Localities for Minasgeraisite-(Y)

    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Brazil
     
    • Southeast Region
      • Minas Gerais
        • Jaguaraçu
    		American Mineralogist, 71, pp. 603-607 (1986); Mineralogical Record - Vol 25 No.3
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