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Fogoite-(Y)

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About Fogoite-(Y)Hide

Formula:
Na3Ca2Y2Ti(Si2O7)2OF3
Colour:
Colourless; creamy white
Lustre:
Vitreous
Hardness:
5
Specific Gravity:
3.523 (Calculated)
Crystal System:
Triclinic
Name:
Named for the type locality - Lagoa do Fogo / Fogo volcano.
Isostructural with:
Chemically close to hainite. May also be compared to batievaite-(Y), which however is devoid of dominant Na.

The structure is, as of many Ti silicates, built of TS (Titanium Silicate) blocks, comprising HOH sheets (H for heteropolyhedral, O for octahedral); HOH || (100). The O sheet, ideal composition Na3Ti(OF)F2, comprises:
- the [6]MO(1) site, mainly Ti
- the [6]MO(2) and [6]MO(3): Na and Na(Mn)
The H sheet, ideal composition Y2Ca2(Si2O7)2, comprises:
- two tetrahedral Si sites, forming disilicate groups
- the [6]MH site: Y(REE,Mn,Zr,etc.)
- the [6]AP site: Ca, = 2.416 Å.



Classification of Fogoite-(Y)Hide

Approved
Approval Year:
2015
First Published:
2017

Physical Properties of Fogoite-(Y)Hide

Vitreous
Transparency:
Transparent
Colour:
Colourless; creamy white
Comment:
generally transparent
Streak:
White
Hardness:
Comment:
ca. 5
Cleavage:
Very Good
{100}
Fracture:
Splintery
Density:
3.523 g/cm3 (Calculated)

Optical Data of Fogoite-(Y)Hide

Type:
Biaxial (+)
RI values:
nα = 1.686(2) nβ = 1.690(2) nγ = 1.702(5)
2V:
Measured: 57° (1), Calculated: 60°
Max Birefringence:
δ = 0.016
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
High
Pleochroism:
Non-pleochroic

Chemical Properties of Fogoite-(Y)Hide

Formula:
Na3Ca2Y2Ti(Si2O7)2OF3
IMA Formula:
Ca2Y2Na3Ti(Si2O7)2(OF)F2
Common Impurities:
Mn,Nb

Crystallography of Fogoite-(Y)Hide

Crystal System:
Triclinic
Class (H-M):
1 - Pedial
Space Group:
P1
Cell Parameters:
a = 9.575(6) Å, b = 5.685(4) Å, c = 7.279(5) Å
α = 89.985(6)°, β = 100.933(4)°, γ = 101.300(5)°
Ratio:
a:b:c = 1.684 : 1 : 1.28
Unit Cell V:
381.2 ų
Z:
1
Morphology:
Prism elongated (on [001]), up to 2000 μm long and 50 x 50 μm in cross-section
Twinning:
twinned

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
3.960(23)
3.069(42)
2.954(100)
2.626(21)
2.486(24)
2.195(17)
1.893(23)
1.820(20)

Type Occurrence of Fogoite-(Y)Hide

General Appearance of Type Material:
Highly elongated [001] prisms, [001] elongation, up to 2 mm in length, up to 50 x 50 μm in cross-section
Place of Conservation of Type Material:
Collections of the Museo Regionale di Scienze Naturali di Torino, Torino, Italy, catalogue numbers M/U 16800 and M/U 16801, the Royal Ontario Museum, Toronto, Ontario, Canada, catalogue number M56826,and the Muséum d’Histoire Naturelle de Paris, catalogue
Geological Setting of Type Material:
Peralkaline volcanic rocks
Associated Minerals at Type Locality:

Synonyms of Fogoite-(Y)Hide

Relationship of Fogoite-(Y) to other SpeciesHide

Other Members of this group:
Batievaite-(Y)Y2Ca2Ti(Si2O7)2(OH)2(H2O)4Tric. 1 : P1
GötzeniteNaCa6Ti(Si2O7)2OF3Tric. 1 : P1
GrenmariteNa4MnZr3(Si2O7)2O2F2Mon. 2/m : P2/b
Hainite-(Y)Na2Ca4(Y,REE)Ti(Si2O7)2OF3Tric. 1 : P1
KochiteNa3Ca2MnZrTi(Si2O7)2OF3Tric. 1 : P1
Mosandrite-(Ce)(Ca3REE)[(H2O)2Ca0.50.5]Ti(Si2O7)2(OH)2(H2O)2Mon. 2/m : P21/b
Nacareniobsite-(Ce)NbNa3Ca3(Ce,REE )(Si2O7)2OF3Mon.
Rinkite-(Ce)(Ca3Ce)Na(NaCa)Ti(Si2O7)2(OF)F2Mon.
Rinkite-(Y)Na2Ca4YTi(Si2O7)2OF3Mon. 2/m : P21/b
RosenbuschiteNa6Ca6Zr3Ti(Si2O7)4O2F6Tric. 1 : P1
Roumaite(Ca,Na,REE,◻)7(Nb,Ti)[Si2O7]2OF3Mon. m : Bb
SeidozeriteNa4MnZr2Ti(Si2O7)2O2F2Mon.

Common AssociatesHide

Associated Minerals Based on Photo Data:
Astrophyllite1 photo of Fogoite-(Y) associated with Astrophyllite on mindat.org.

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 Fogoite-(Y)Hide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Cámara, F., Sokolova, E., Abdu, Y.A., Hawthorne, F.C., Charrier, T., Dorcet, V., Carpentier, J.-F. (2015) Fogoite-(Y), IMA 2014-098. CNMNC Newsletter No. 24, April 2015, page 250. Mineralogical Magazine: 79: 247-251.
Cámara, F., Sokolova, E., Abdu, Y.A., Hawthorne, F.C., Charrier, T., Dorcet, V., Carpentier, J.-F. (2017): Fogoite-(Y), Na3Ca2Y2Ti(Si2O7)2OF3, a Group-I TS-block mineral from the Lagoa do Fogo, the Fogo volcano, the São Miguel Island, the Azores: Description and crystal structure. Mineralogical Magazine 81, 369-381.
Sokolova, E. & Camara, F. (2017): The seidozerite supergroup of TS-block minerals: nomenclature and classification, with change of the following names: rinkite to rinkite-(Ce), mosandrite to mosandrite-(Ce), hainite to hainite-(Y) and innelite-1T to innelite-1A. Mineralogical Magazine: 81 (in press)

Internet Links for Fogoite-(Y)Hide

Localities for Fogoite-(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.
Portugal (TL)
 
  • Azores
    • São Miguel Island
      • Água de Pau Massif
        • Água de Pau Volcano (Fogo Volcano)
          • Lake Fogo
Cámara, F., Sokolova, E., Abdu, Y.A., Hawthorne, F.C., Charrier, T., Dorcet, V. and Carpentier, J.-F. (2015) Fogoite-(Y), IMA 2014-098. CNMNC Newsletter No. 24, April 2015, page 250; Mineralogical Magazine, 79, 247-251.; Cámara, F., Sokolova, E., Abdu, Y.A., Hawthorne, F.C., Charrier, T., Dorcet, V., Carpentier, J.-F. (2017): Fogoite-(Y), Na3Ca2Y2Ti(Si2O7)2OF3, a Group-I TS-block mineral from the Lagoa do Fogo, the Fogo volcano, the São Miguel Island, the Azores: Description and crystal structure. Mineralogical Magazine, 81, 369–381
Mineral and/or Locality  
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