Fogoite-(Y)
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About Fogoite-(Y)
view of the "Fogo lake"
Lake Fogo, Água de Pau Volcano, Água de Pau Massif, São Miguel Island, Azores, Portugal
Lake Fogo, Água de Pau Volcano, Água de Pau Massif, São Miguel Island, Azores, Portugal
Formula:
Na3Ca2Y2Ti(Si2O7)2OF3
Colour:
Colourless; creamy white
Lustre:
Vitreous
Hardness:
5
Specific Gravity:
3.523 (Calculated)
Crystal System:
Triclinic
Member of:
Name:
Named for the type locality - Lagoa do Fogo / Fogo volcano.
Type Locality:
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.
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)
Physical Properties of Fogoite-(Y)
Vitreous
Transparency:
Transparent
Colour:
Colourless; creamy white
Comment:
generally transparent
Streak:
White
Hardness:
5 on Mohs scale
Comment:
ca. 5
Cleavage:
Very Good
{100}
{100}
Fracture:
Splintery
Density:
3.523 g/cm3 (Calculated)
Optical Data of Fogoite-(Y)
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.
and does not take into account mineral colouration.
Surface Relief:
High
Pleochroism:
Non-pleochroic
Chemical Properties of Fogoite-(Y)
Formula:
Na3Ca2Y2Ti(Si2O7)2OF3
IMA Formula:
Ca2Y2Na3Ti(Si2O7)2(OF)F2
Common Impurities:
Mn,Nb
Crystallography of Fogoite-(Y)
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)°
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 Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 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)
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)
Relationship of Fogoite-(Y) to other Species
Member of:
Other Members of this group:
| Batievaite-(Y) | Y2Ca2Ti(Si2O7)2(OH)2(H2O)4 | Tric. 1 : P1 |
| Götzenite | NaCa6Ti(Si2O7)2OF3 | Tric. 1 : P1 |
| Grenmarite | Na4MnZr3(Si2O7)2O2F2 | Mon. 2/m : P2/b |
| Hainite-(Y) | Na2Ca4(Y,REE)Ti(Si2O7)2OF3 | Tric. 1 : P1 |
| Kochite | Na3Ca2MnZrTi(Si2O7)2OF3 | Tric. 1 : P1 |
| Mosandrite-(Ce) | (Ca3REE)[(H2O)2Ca0.5☐0.5]Ti(Si2O7)2(OH)2(H2O)2 | Mon. 2/m : P21/b |
| Nacareniobsite-(Ce) | NbNa3Ca3(Ce,REE )(Si2O7)2OF3 | Mon. |
| Rinkite-(Ce) | (Ca3Ce)Na(NaCa)Ti(Si2O7)2(OF)F2 | Mon. |
| Rinkite-(Y) | Na2Ca4YTi(Si2O7)2OF3 | Mon. 2/m : P21/b |
| Rosenbuschite | Na6Ca6Zr3Ti(Si2O7)4O2F6 | Tric. 1 : P1 |
| Roumaite | (Ca,Na,REE,◻)7(Nb,Ti)[Si2O7]2OF3 | Mon. m : Bb |
| Seidozerite | Na4MnZr2Ti(Si2O7)2O2F2 | Mon. |
Common Associates
Associated Minerals Based on Photo Data:
| Astrophyllite | 1 photo of Fogoite-(Y) associated with Astrophyllite on mindat.org. |
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.
References for Fogoite-(Y)
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)
mindat.org URL:
https://www.mindat.org/min-46576.html
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Localities for Fogoite-(Y)
symbol to view information about a locality.
The Locality List
- 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).
All localities listed without proper references should be considered as questionable.
Portugal (TL) | |
| 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 |
Near the ruins of Lombadas, Lake Fogo, Água de Pau Volcano, Água de Pau Massif, São Miguel Island, Azores, Portugal