Abenakiite-(Ce)

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.

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).

Notes on chemistry and relation to other species

Combination of elements in abenakiite-(Ce) is unique. Somewhat chemically similar mineral is steenstrupine-(Ce). 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.

Crystal structure

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

• 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

• List of minerals

References

External links

• Mindat.org
• Webmineral.org