abenakiite-(Ce)

{{Infobox mineral | name = Abenakiite-(Ce) | boxwidth = | boxbgcolor = | image = أبيناكييت.jpg | imagesize = | alt = | caption = | category = Silicate, cyclosilicate | formula = Na26Ce6(SiO3)6(PO4)6(CO3)6(S4+O2)O |IMAsymbol=Abk-Ce | molweight = | strunz = 9.CK.10 | system = Trigonal | class = Rhombohedral () H-M symbol: () | symmetry = R | unit cell = a = 16.02, c = 19.76 [Å], Z = 3 | color = Pale brown | colour =, to dark brown | habit = Euhedral Crystals - Occurs as well-formed crystals showing good external form. | twinning = | cleavage = {0001}, poor | fracture = Conchoidal | tenacity = | mohs = 4–5 | luster = Vitreous | streak = White | diaphaneity = Transparent | gravity = 3.32 gm/cc. | density = 3.21 | polish = | opticalprop = Uniaxial (−) | refractive = nω=1.59, nε=1.57 | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = Radioactive | prop1 = | prop1text = | references = }} 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).