Ilyukhinite (H3O,Na)14Ca6Mn2Zr3Si26O72(OH)2 ∙ 3H2O, a New Mineral of the Eudialyte Group

New Data on the Isomorphism in Eudialyte-Group Minerals. 1. Crystal Chemistry of Eudialyte-Group Members with Na Incorporated into the Framework as a Marker of Hyperagpaitic Conditions

“…[10] Note: Roman numerals denote coordination numbers. A part of the data corresponds to holotype samples of EGMs: raslakite (12), sergevanite (13), aqualite (14), alluaivite (17), dualite (19), labirinthite (20) and rastsvetaevite (21).…”

New Data on the Isomorphism in Eudialyte-Group Minerals. 2. Crystal-Chemical Mechanisms of Blocky Isomorphism at the Key Sites

“…Mn-dominant V M2 site occurs in the structure of andrianovite [30,31]. In the ilyukhinite structure [47,48] the М2 site has a fourfold flat-square coordination with the М2-О distances of 2.11-2.51 Å and is predominantly occupied by Mn with a minor Fe The fourfold (nearly, flat-square) coordination is most typical for Fe 2+ and, to a less extent, for Na. In particular, eudialyte s.s. is M2 ( IV Fe 2+ )-dominant [16,17].…”

“…The fivefold M2-centered polyhedron is a square pyramid M2O 4 Ø (Figure 3) where O atoms belong to the neighboring M1 6 O 24 rings and Ø is OH group of the M3O 3 (OH) 3 4a) was the first EGM in which such polyhedron was identified [29]. Later, V M2 site was found in different EGMs [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. Mn-dominant V M2 site occurs in the structure of andrianovite [30,31].…”

“…Mn-dominant V M2 site occurs in the structure of andrianovite [30,31]. In the ilyukhinite structure [47,48] the M2 site has a fourfold flat-square coordination with the M2-O distances of 2.11-2.51 Å and is predominantly occupied by Mn with a minor Fe admixture. The replacement of manganese with iron at the fivefold M2 site has been established in a number of minerals close in structure to kentbrooksite including ferrokentbrooksite [32], georgbarsanovite [33,34], taseqite [35,36], feklichevite [37], golyshevite [38,39], as well as some varieties of other EGMs [1].…”

Eudialyte-group minerals from the Monte de Trigo alkaline suite, Brazil: composition and petrological implications

“…According to the International Mineralogical Association (Johnsen et al 2003), the general formula of the EGMs is Na 12 [N(4) 4 X 2 , in which the common elements assigned to each site are as it follows: ■ Si at M(4); ■ Nb, Si,Ti,and W at M(3); ■ Fe, Mn, Na, Zr, K, and H 3 O at M(2); ■ Ca, Mn, and Fe at M(1); ■ Na, REE,Sr,K,Ca,Mn,and H 3 O at N(4); ■ Cl, OH, F, and CO 3 at X. Rastsvetaeva & Chukanov (2012) list 25 known species of EGMs, and recently a new member named Ilyukhinite was described (Chukanov et al 2015). This great diversity is the result of the compositional and structural complexity of the group.…”