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Abenakiite-(Ce)

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Abenakiite-(Ce)
General
CategorySilicate, cyclosilicate
Formula
(repeating unit)
Na26Ce6(SiO3)6(PO4)6(CO3)6(S4+O2)O
IMA symbolAbk-Ce[1]
Strunz classification9.CK.10
Crystal systemTrigonal
Crystal classRhombohedral (3)
H-M symbol: (3)
Space groupR3
Unit cella = 16.02, c = 19.76 [Å], Z = 3
Identification
ColorPale brown
Cleavage{0001}, poor
FractureConchoidal
Mohs scale hardness4–5
LusterVitreous
StreakWhite
Specific gravity3.21 (meas.), 3.27 (calc.)
Optical propertiesUniaxial (−)
Refractive indexnω=1.59, nε=1.57
References[2][3]

Abenakiite-(Ce) is a mineral of sodium, cerium, neodymium, lanthanum, praseodymium, thorium, samarium, oxygen, sulfur, carbon, phosphorus, and silicon with a chemical formula Na26Ce6(SiO3)6(PO4)6(CO3)6(S4+O2)O. The silicate groups may be given as the cyclic Si6O18 grouping. The mineral is named after the Abenaki, an Algonquian Indian tribe of New England. Its Mohs scale rating is 4 to 5.[2]

Occurrence and association

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Abenakiite-(Ce) was discovered in a sodalite syenite xenolith at Mont Saint-Hilaire, Québec, Canada, together with aegirine, eudialyte, manganoneptunite, polylithionite, serandite, and steenstrupine-(Ce).[2][3]

Notes on chemistry and relation to other species

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Combination of elements in abenakiite-(Ce) is unique. Somewhat chemically similar mineral is steenstrupine-(Ce).[3][4] The hyper-sodium abenakiite-(Ce) is also unique in supposed presence of sulfur dioxide ligand. With a single grain (originally) found, abenakiite-(Ce) is extremely rare.[2]

Crystal structure

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In the crystal structure, described as a hexagonal net, of abenakiite-(Ce) there are:[2]

  • chains of NaO7 polyhedra, connected with PO4 groups
  • columns with six-membered rings of NaO7, and NaO7-REEO6, and SiO4 polyhedra (REE – rare earth elements)
  • CO3 groups, NaO6 octahedra, and disordered SO2 ligands within the columns

See also

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References

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  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c d e McDonald, A.M.; Chao, G.Y.; Grice, J.D. (1994). "Abenakiite-(Ce), a new silicophosphate carbonate mineral from Mont Saint-Hilaire, Quebec: Description and structure determination" (PDF). The Canadian Mineralogist. 32: 843–854.
  3. ^ a b c "Abenakiite-(Ce)". mindat.org. Retrieved 2024-05-25.
  4. ^ "[International Mineralogical Association] : List of Minerals – IMA". Ima-mineralogy.org. Retrieved 2016-03-12.
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