Carbokentbrooksite
A very rare carbonate-bearing member of the eudialyte group with an exceptionally complex formula.
Intro adapted from Wikipedia (CC BY-SA).
Carbokentbrooksite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Na, )₁₂(Na,Ce)₃Ca₆Mn₃Zr₃NbSi₂₅O₇₃(OH)₃(CO₃)·H₂O.
It crystallizes in the hexagonal crystal system (space group R3m). It is a member of the Eudialyte structural group.
Key properties: Mohs hardness 5; specific gravity 3.14; White streak; Vitreous luster; optically uniaxial.
IMA symbol Cktb, IMA status: approved, named in 2002.
Found in the quartz core of a zoned pegmatite in the Dara-i-Pioz alkaline massif.
It is found associated with Zirsilite-(Ce), quartz, microcline, aegirine, stillwellite-(Ce), ekanite, polylithionite, pyrochlore, fluorite, calcite, galena.
The name refers to the compositional relationship (carbonate) to kentbrooksite.