Feklichevite is a rare mineral of the

eudialyte group Eudialyte group is a group of complex trigonal zircono- and, more rarely, titanosilicate minerals with general formula (1)N(2)N(3)N(4)N(5)sub>3 (1a)M(1b)sub>3M(2)3M(4)Z3 i24O72'4X2, where N(1) and N(2) and N(3) and N(5) = Na+ and more rarely H3 ...

with the formula Na₁₁Ca₉(Fe³⁺,Fe²⁺)₂Zr₃NbSi(Si₃O₉)₂(Si₉O₂₇)₂.Pekov, I.V., Ekimenkova, I.A., Chukanov, N.V., Rastsvetaeva, R.K., Kononkova, N.N., Pekova, N.A., and Zadov, A.E., 2001. Feklichevite Na₁₁Ca₉(Fe³⁺,Fe²⁺)₂Zr₃Nb i₂₅O₇₃OH,H₂O,Cl,O)₅, a new mineral of the eudialyte group from Kovdor Massif, Kola peninsula. Zapiski Vserossijskogo Mineralogicheskogo Obshchestva 130(3), 55-65Mindat, Feklichevite, http://www.mindat.org/min-11029.html The original formula was extended to show the presence of cyclic silicate groups and presence of silicon at the M4 site, according to the nomenclature of eudialyte group.Johnsen, O., Ferraris, G., Gault, R.A., Grice, D.G., Kampf, A.R., and Pekov, I.V., 2003. The nomenclature of eudialyte-group minerals. The Canadian Mineralogist 41, 785-794 When compared to other minerals of the group, feklichevite characterizes in the presence of ferric iron (thus similar to

ikranite Ikranite is a member of the eudialyte group, named after the Shubinov Institute of Crystallography of the Russian Academy of Sciences. It is a cyclosilicate mineral that shows trigonal symmetry with the space group ''R''3''m'', and is often seen ...

, mogovidite and

fengchengite Fengchengite is a rare mineral of the eudialyte groupMindat, Fengchengite, http://www.mindat.org/min-42378.html with the formula .Shen, G., Xu, J., Yao, P., and Li, G., 2011. Fengchengite, IMA 2007-018a. CNMNC Newsletter No. 11, December 2011, 289 ...

) and dominance of calcium at the N4 site. Calcium is ordered in the structure and is also present at the M1 site. Other iron-bearing minerals of the group are eudialyte,

ferrokentbrooksite Ferrokentbrooksite is a moderately rare mineral of the eudialyte group,Mindat, Ferrokentbrooksite, http://www.mindat.org/min-7106.html with formula .Johnsen, O., Grice, J.D., and Gault, R.A., 2003: Ferrokentbrooksite, a new member of the eudialyte ...

georgbarsanovite Georgbarsanovite is a very rare mineral of the eudialyte group,Mindat, http://www.mindat.org/min-27506.html formerly known under unaccepted name as barsanovite, with formula .Khomyakov, A.P., Nechelyustov, G.N., Ekimenkova, I.A., and Rastsvetayeva ...

, khomyakovite,

labyrinthite Labyrinthite is a very rare mineral of the eudialyte group.Mindat, http://www.mindat.org/min-27420.html When compared to other species in the group, its structure is extremely complex - with over 100 sites and about 800 cations and anions - hence ...

oneillite Oneillite is a rare mineral of the eudialyte group with the chemical formula .Mindat, Oneillite, http://www.mindat.org/min-11029.htmlJohnsen, O., Grice, J.D., and Gault, R.A., 1999. Oneillite: a new Ca-deficient and ''REE''-rich member of the eud ...

and rastsvetaevite, but they rather contain ferrous iron Feklichevite name honors Russian mineralogist and crystallographer, V. G. Feklichev.

Occurrence and association

Feklichevite was found in cancrinite

syenite Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). Some syenites contain larger proport ...

vein of pegmatoid type, that occurs in the Kovdor alkaline massif, Kola Peninsula, Russia. Feklichevite coexists with aegirine- diopside, cancrinite, potassic

feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldsp ...

, pectolite,

titanite Titanite, or sphene (from the Greek ''sphenos'' (σφηνώ), meaning wedge), is a calcium titanium nesosilicate mineral, Ca Ti Si O5. Trace impurities of iron and aluminium are typically present. Also commonly present are rare earth metals in ...

hematite Hematite (), also spelled as haematite, is a common iron oxide compound with the formula, Fe2O3 and is widely found in rocks and soils. Hematite crystals belong to the rhombohedral lattice system which is designated the alpha polymorph of . ...

, and руrrhоtitе.

Notes on chemistry

Feklichevite has quite high admixtures of

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

and

fluorine Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reacti ...

, with minor

hafnium Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri M ...

strontium Strontium is the chemical element with the symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly chemically reactive. The metal forms a dark oxide layer when it is ex ...

titanium Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...

cerium Cerium is a chemical element with the symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the +3 o ...

, and

lanthanum Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lantha ...

References

Cyclosilicates Sodium minerals Calcium minerals Iron(II,III) minerals Zirconium minerals Niobium minerals Trigonal minerals Minerals in space group 160 {{silicate-mineral-stub