Reederite-(Y)
Reederite-(Y) is a rare mineral with the formula (Na,Mn,Fe)15(Y,REE)2(CO3)9(SO3F)Cl. It is the only known mineral with fluorosulfate (fluorosulfonate). "REE" in the formula stands for rare earth elements other than yttrium, that is mostly cerium, with traces of neodymium, dysprosium, lanthanum and erbium. The formula also includes a Levinson suffix "-(Y)" pointing to the dominance of yttrium at the corresponding site. Reederite-(Y) crystallizes in the hexagonal crystal system with the space group P6, rarely seen among minerals.
Intro adapted from Wikipedia (CC BY-SA).
Reederite-(Y) is an IMA-recognized mineral species in the sulfate class, with the chemical formula (Na,Mn)₁₅Y₂(CO₃)₉(SO₃F)Cl.
It crystallizes in the hexagonal crystal system (space group P-6).
Key properties: Mohs hardness 3–3.5; specific gravity 2.91; White streak; Vitreous luster; optically uniaxial.
IMA symbol Rde-Y, IMA status: approved, named in 1994.
Found as a very rare mineral in a sodalite xenolith in syenite in an intrusive alkalic gabbro-syenite complex.
It is found associated with Trona, shortite, petersenite-(Ce), catapleiite, analcime, manganotychite.
The mineral was named to honor Dr. Richard James Reeder (1953–), Professor of Geochemistry, State University of New York, Stony Brook, New York, USA, for his contributions to carbonate mineralogy.