Log In
Cayalsite-(Y)
A valid IMA mineral species
This page is currently not sponsored. Click here to sponsor this page.
About Cayalsite-(Y)
Formula:
CaY6Al2Si4O18F6
Colour:
Colourless to faintly pink
Lustre:
Vitreous
Hardness:
6½
Specific Gravity:
4.81 - 4.86
Crystal System:
Orthorhombic
Name:
Name after the chemical composition: Ca(lcium)Y(ttrium)Al(uminium)Si(licon).
Two maximum degree of order (MDO) polytypic modifications, cayalsite-(Y)-1O and cayalsite-(Y)-1M, are known. The element combination is slightly similar to that in (more complex) hundholmenite-(Y), but there is no relation between these minerals.
Crystal structure details/elements:
- linear chains of AlO6 octahedra that share edges
- isolated SiO4 tetrahedra
- REE and Ca, substitutionally disordered, have both the coordination number 8, being surrounded by O and F anions
- substitutional and positional disorder of the silicate tetrahedra in one of silicate-bearing layers
- no close Si-F contacts -> partial splitting of the position of O and F atoms.
Crystal structure details/elements:
- linear chains of AlO6 octahedra that share edges
- isolated SiO4 tetrahedra
- REE and Ca, substitutionally disordered, have both the coordination number 8, being surrounded by O and F anions
- substitutional and positional disorder of the silicate tetrahedra in one of silicate-bearing layers
- no close Si-F contacts -> partial splitting of the position of O and F atoms.
Unique Identifiers
Mindat ID:
42752
Long-form identifier:
mindat:1:1:42752:2
IMA Classification of Cayalsite-(Y)
Classification of Cayalsite-(Y)
9.A0.05
9 : SILICATES (Germanates)
A : Nesosilicates
0 :
9 : SILICATES (Germanates)
A : Nesosilicates
0 :
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 |
|---|---|---|
| Cyl-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 Cayalsite-(Y)
Vitreous
Colour:
Colourless to faintly pink
Streak:
White
Hardness:
6½ on Mohs scale
Hardness:
VHN100=1049 - Vickers
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Irregular/Uneven
Density:
4.81 - 4.86 g/cm3 (Measured)
Optical Data of Cayalsite-(Y)
Type:
Biaxial (+)
RI values:
nα = 1.730(5) nβ = 1.740(5) nγ = 1.760(5)
2V:
Measured: 56.5° (5), Calculated: 71.2°
Max. Birefringence:
δ = 0.030
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. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
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. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Chemistry of Cayalsite-(Y)
Mindat Formula:
CaY6Al2Si4O18F6
Element Weights:
Crystallography of Cayalsite-(Y)
Polytype:
Formula:
Crystal System:
Class (H-M)
Space Group:
Space Group Setting:
Cell Parameters:
Ratio:
Unit Cell Volume (calc):
Z:
Comment:
| Cayalsite-(Y)-1M | Cayalsite-(Y)-1O |
|---|---|
| CaY6Al2Si4O18F6 | CaY6Al2Si4O18F6 |
| Monoclinic | Orthorhombic |
| 2/m - Prismatic | mmm(2/m2/m2/m) - Dipyramidal |
| P2/b | Pban |
| P2/c | Pban |
| a = 11.0602(7) Å, b = 5.5280(2) Å, c = 16.0195(9) Å β = 118.925(3)° | a = 15.993(1) Å, b = 5.5306(3) Å, c = 9.6590(7) Å |
| a:b:c = 2.001 : 1 : 2.898 | a:b:c = 2.892 : 1 : 1.746 |
| V 857.26 ų (Calculated from Unit Cell) | V 854.35 ų (Calculated from Unit Cell) |
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 5.222 Å | (22) |
| 4.584 Å | (15) |
| 4.094 Å | (17) |
| 3.997 Å | (16) |
| 3.547 Å | (58) |
| 2.992 Å | (100) |
| 2.776 Å | (15) |
| 2.727 Å | (15) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 4b: Highly evolved igneous rocks | >3.0 |
| 34 : Complex granite pegmatites |
Geological Setting:
In cavities in yttrian fluorite in granitic pegmatite
Type Occurrence of Cayalsite-(Y)
Co-Type Localities:
General Appearance of Type Material:
prismatic crystals in small cavities of yttrian fluorite, sometimes forming radiating aggregates.
Place of Conservation of Type Material:
Mineralogical Museum of the University of Hamburg, Grindelallee 48, D-20146 Hamburg, Germany, catalogue numbers NO-002B/08 (1O polytype) and NO-002/08 (1M polytype)
Geological Setting of Type Material:
NYF-pegmatites
Associated Minerals at Type Locality:
Synonyms of Cayalsite-(Y)
Other Language Names for Cayalsite-(Y)
Dutch:Cayalsiet-(Y)
German:Cayalsit-(Y)
Common Associates
Associations Based on Photo Data:
| 1 photo of Cayalsite-(Y) associated with 'Yttrofluorite' | (Ca1-xYx)F2+x where 0.05 < x < 0.3 |
Related Minerals - Strunz-mindat Grouping
| 9.A0. | Atelisite-(Y) | Y4Si3O8(OH)8 |
Fluorescence of Cayalsite-(Y)
none
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 Cayalsite-(Y)
mindat.org URL:
https://www.mindat.org/min-42752.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
External Links:
Mineral Dealers:
References for Cayalsite-(Y)
Reference List:
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2012) New minerals and nomenclature modifications approved in 2012. CNMNC Newsletter No 13. Mineralogical Magazine, 76 (3) 807-817 doi:10.1180/minmag.2012.076.3.26
Localities for Cayalsite-(Y)
Showing 6 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.
Norway (TL) | |
| [Cayalsite-(Y)-1O] Williams et al. (2012) +1 other reference |
| Husdal (2019) +1 other reference |
| [Cayalsite-(Y)-1M, Cayalsite-(Y)-1O] Williams et al. (2012) +2 other references |
Quick NavTopAbout Cayalsite-(Y)Unique IdentifiersIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesCommon AssociatesStrunz-MindatFluorescence Other InformationInternet Links References Localities Locality List
Øvre Lapplægeret Quarry, Lapplægeret, Drag, Hamarøy, Nordland, Norway