Chemistry:Abenakiite-(Ce)
| Abenakiite-(Ce) | |
|---|---|
 | |
| General | |
| Category | Silicate, cyclosilicate |
| Formula (repeating unit) | Na26Ce6(SiO3)6(PO4)6(CO3)6(S4+O2)O |
| Strunz classification | 9.CK.10 |
| Crystal system | Trigonal |
| Crystal class | Rhombohedral (3) H-M symbol: (3) |
| Space group | R3 |
| Unit cell | a = 16.02, c = 19.76 [Å], Z = 3 |
| Identification | |
| Color | Pale brown |
| Cleavage | {0001}, poor |
| Fracture | Conchoidal |
| Mohs scale hardness | 4–5 |
| |re|er}} | Vitreous |
| Streak | White |
| Specific gravity | 3.21 (meas.), 3.27 (calc.) |
| Optical properties | Uniaxial (-) |
| Refractive index | nω=1.59, nε=1.57 |
| References | [1][2] |
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.[1]
Occurrence and association
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).[1][2]
Notes on chemistry and relation to other species
Combination of elements in abenakiite-(Ce) is unique. Somewhat chemically similar mineral is steenstrupine-(Ce).[2][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.[1]
Crystal structure
In the crystal structure, described as a hexagonal net, of abenakiite-(Ce) there are:[1]
- 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
References
- ↑ 1.0 1.1 1.2 1.3 1.4 McDonald, A.M., Chao, G.Y., and Grice, J.D., 1994. Abenakiite-(Ce), a new silicophosphate carbonate mineral from Mont Saint-Hilaire, Quebec: Description and structure determination. The Canadian Mineralogist 32, 843–854
- ↑ 2.0 2.1 2.2 Mindat, Abenakiite-(Ce), Mindat.org
- ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode: 2021MinM...85..291W.
- ↑ "[International Mineralogical Association : List of Minerals – IMA"]. http://www.ima-mineralogy.org/Minlist.htm. Retrieved 2016-03-12.
External links
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