**2.2.7. Kuannersuite-(Ce)**

The mineral kuannersuite-(Ce) (Na2Ce2Ba6(PO4)6FCl [88]) was found and named according to the locality (Kuannersuit plateau) in the Ilímaussaq alkaline complex, South Greenland (**Fig. 27**). It occurs associated with the minerals including aegirine, analcime, beryllite (Be3SiO4(OH)2·H2O [89]), chkalovite, galena, gmelinite17 [90],[91],[92],[93], gonnardite ((Na,Ca)2(Si,Al)5O10·3H2O [94]), lovdarite (K2Na6Be4Si14O36·9H2O [95],[96]), nabesite (Na2BeSi4O10·4H2O [97],[98]), neptunite, pectolite, polylithionite (KLi2AlSi4O10F2 [99]), pyro‐ chlore18 [100], sphalerite (ZnS [101]) and tugtupite.

**Fig. 27** The locality for the mineral kuannersuite-(Ce).

<sup>17</sup> There are three minerals: gmelinite-(Ca), gmelinite-(K), and gmelinite-(Na) with the composition of Ca2(Si8Al4)O24·11H2O [90],[91], K4(Si8Al4)O24·11H2O [93], and Na4(Si8Al4)O24·11H2O [91],[93], respectively.

<sup>18</sup> The member of the pyrochlore group ((Na,Ca)2Nb2O6(OH,F)). A new scheme of nomenclature for the pyrochlore supergroup, approved by the CNMNC–IMA, is based on the ions at the A, B, and Y sites. The subgroups should be changed to the groups: pyrochlore (1), microlite (2), roméite (3), betafite (4), and elsmoreite (5). The new names are composed of two prefixes and one root name (identical to the name of the group). The first prefix refers to the dominant anion (or cation) of the dominant valence [either H2O or □] at the Y site. The second prefix refers to the dominant cation of the dominant valence [either H2O or □] at the A site. The prefix "keno–" represents "vacancy." Where the first and the second prefix are equal, only one prefix is applied [100].

It occurs as light rose-colored hexagonal prismatic crystals, up to 1.5 mm long, with a white streak and a vitreous luster. It is a barium analogue of belovite-(Ce) (**Section 2.2.1**) and NaCeBa3 analogue of fluorapatite (**Section 1.5.1**). The mineral is brittle and shows poor cleavage along {001} and {100}. The structure and the crystal habit of the mineral kuanner‐ suite-(Ce) are shown in **Fig. 28**.

**Fig. 28** The structure and the crystal habit of the mineral kuannersuite-(Ce).

Kuannersuite-(Ce) crystallizes in trigonal systems with the space group P3 ¯. The parameters of unit cell are: *a* = 9.9097 and *c* = 7.4026 Å, *V* = 629.558 Å3 and *Z* = 2. There is no fluorescence under ultraviolet light (long or short wave). The Mohs hardness of kuannersuite is between 4½ and 5½, and calculated density is 4.5 g⋅cm−3.
