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About Cayalsite-(Y)Hide

Colourless to faintly pink
Specific Gravity:
4.81 - 4.86
Crystal System:
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.

Classification of Cayalsite-(Y)Hide

Approval year:

Physical Properties of Cayalsite-(Y)Hide

Colourless to faintly pink
6½ on Mohs scale
VHN100=1049 - Vickers
None Observed
4.81 - 4.86 g/cm3 (Measured)    

Optical Data of Cayalsite-(Y)Hide

Biaxial (+)
RI values:
nα = 1.730(5) nβ = 1.740(5) nγ = 1.760(5)
Measured: 56.5° (5), Calculated: 71.2°
Max Birefringence:
δ = 0.030
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:

Chemical Properties of Cayalsite-(Y)Hide

IMA Formula:

Crystallography of Cayalsite-(Y)Hide

Crystal System:
Class (H-M)
Space Group:
Space Group Setting:
Cell Parameters:
Unit Cell Volume (calc):
Monoclinic Orthorhombic 
2/m - Prismaticmmm (2/m 2/m 2/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 : 2.898a: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 DiffractionHide

Powder Diffraction Data:
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 EnvironmentHide

Paragenetic Mode(s):
Geological Setting:
In cavities in yttrian fluorite in granitic pegmatite

Type Occurrence of Cayalsite-(Y)Hide

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:
Associated Minerals at Type Locality:

Synonyms of Cayalsite-(Y)Hide

Common AssociatesHide

Associated Minerals Based on Photo Data:
2 photos of Cayalsite-(Y) associated with Yttrofluorite(Ca1-xYx)F2+x where 0.05< x

Fluorescence of Cayalsite-(Y)Hide

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 Cayalsite-(Y)Hide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Malcherek, T., Schlüter, J., Husdal, T.A., Cooper, M.A. (2012) Cayalsite-(Y), IMA 2011-094. CNMNC Newsletter No. 13, June 2012, page 814; Mineralogical Magazine, 76, 807-817.
Malcherek, T., Schlüter, J., Cooper, M.A., Ball, N., Husdal, T. (2015): Cayalsite-(Y), a new rare earth calcium aluminium fluorosilicate with OD character. European Journal of Mineralogy, 27, 683-694.

Internet Links for Cayalsite-(Y)Hide

Localities for Cayalsite-(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.
Norway (TL)
  • Nordland
    • Hamarøy
      • Drag
        • Lapplægeret
Malcherek, T., Schlüter, J., Cooper, M.A., Ball, N., Husdal, T. (2015): Cayalsite-(Y), a new rare earth calcium aluminium fluorosilicate with OD character. European Journal of Mineralogy, 27, 683-694.
    • Narvik
Husdal, T. (2019) Nyfunn av mineraler fra Tysfjord-pegmatittene, Nordland. Norsk Mineralsymposium 2019: 31-46
Malcherek, T., Schlüter, J., Cooper, M.A., Ball, N., Husdal, T. (2015): Cayalsite-(Y), a new rare earth calcium aluminium fluorosilicate with OD character. European Journal of Mineralogy, 27, 683-694
Mineral and/or Locality  
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