:Zirsilite-(Ce) is an exceptionally rare complex cyclosilicate that is only found in four localities in the world. The type locality is in Tajikistan, but some of the best known specimens are those from the Sagasen Quarry in Norway. The species gets its name from its chemical composition of zirconium (Zr), silicon (Si) and cerium (Ce). The piece hosts micro burnt orange zirsilite-(Ce) with black aegirine on sodalite matrix. We have photographed the specimen with a Canon MP-E 65 mm macro lens to better illustrate the quality and enhance the detail. Size: 4.1 x 4.1 x 2.3 cm. Locality: Sagåsen Quarry, Sagåsen, Mørje, Porsgrunn, Telemark, Norway — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Zirsilite-(Ce)
Zirsilite-(Ce) is a very rare mineral of the eudialyte group, with formula (Na,□)12(Ce,Na)3Ca6Mn3Zr3NbSi(Si9O27)2(Si3O9)2O(OH)3(CO3)·H2O. The original formula was extended to show the presence of cyclic silicate groups and the presence of silicon at the M4 site, according to the nomenclature of the eudialyte group. Zirsilite-(Ce) differs from carbokentbrooksite in cerium-dominance over sodium only. Both minerals are intimately associated.
Intro adapted from Wikipedia (CC BY-SA).
Zirsilite-(Ce) is an IMA-recognized mineral species in the silicate class, with the chemical formula (Na, )₁₂(Ce,Na)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 3.15; White streak; Vitreous luster; optically uniaxial.
IMA symbol Zir-Ce, 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 Carbokentbrooksite, quartz, microcline, aegirine, stillwellite-(Ce), ekanite, pyrochlore, polylithionite, fluorite, calcite, galena.
The name refers to the essential composition, zirconium silicate and the suffix indicates cesium as the dominant rare earth element.