Summary
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]
| Abenakiite-(Ce) | |
|---|---|
 | |
| General | |
| Category | Silicate, cyclosilicate |
| Formula (repeating unit) | Na26Ce6(SiO3)6(PO4)6(CO3)6(S4+O2)O |
| IMA symbol | Abk-Ce[1] |
| 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 |
| Luster | Vitreous |
| Streak | White |
| Specific gravity | 3.21 (meas.), 3.27 (calc.) |
| Optical properties | Uniaxial (-) |
| Refractive index | nω=1.59, nε=1.57 |
| References | [2][3] |
Occurrence and association edit
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 edit
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 edit
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 edit
References edit
- ^ 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.
- ^ a b c d e 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
- ^ a b c Mindat, Abenakiite-(Ce), Mindat.org
- ^ "[International Mineralogical Association] : List of Minerals – IMA". Ima-mineralogy.org. Retrieved 2016-03-12.
External links edit
Media related to Abenakiite-(Ce) at Wikimedia Commons- Mindat.org
- Webmineral.org
