The seidozerite supergroup of TS-block minerals: nomenclature and classification, with change of the following names: rinkite to rinkite-(Ce), mosandrite to mosandrite-(Ce), hainite to hainite-(Y) and innelite-1T to innelite-1A

Abstract

Here we report a nomenclature and classification for the seidozerite-supergroup minerals. The TS (Titanium-Silicate) block is the main structural unit in all seidozerite-supergroup structures; it consists of a central O (O = Octahedral) sheet and two adjacent H (H = Heteropolyhedral) sheets where Si2O7groups occur in the H sheets. The TS block is characterized by a planar minimal cell based on translation vectors, t1and t2, the lengths of these vectors are t1 ≈ 5.5 and t2 ≈ 7 Å, and t1 ^ t2 is close to 90°. The forty-five minerals of the sedozerite supergroup are divided into four groups based on the content of Ti and topology and stereochemistry of the TS block: in rinkite, bafertisite, lamprophyllite and murmanite groups, Ti (+ Nb + Zr + Fe3++Mg + Mn) = 1, 2, 3 and 4 apfu (atoms per formula unit), respectively. All TS-block structures consist either solely of TS blocks or of two types of block: the TS block and an I (Intermediate) block that comprises atoms between two TS blocks. Usually, the I block consists of alkali and alkaline-earth cations, H2O groups and oxyanions (PO4)3-, (SO4)2-and (CO3)2-.The general formula of the TS block is as follows AP2BP2MH2MO4(Si2O7)2X4+n, where MH2and MO4= cations of the H and O sheets; MH = Ti, Nb, Zr, Y, Mn, Ca + REE, Ca;MO = Ti, Zr, Nb, Fe3+, Fe2+, Mg, Mn, Zn, Ca, Na; AP and BP = cations at the peripheral (P) sites = Na, Ca + REE, Ca, Zn, Ba, Sr, K; X = anions = O, OH, F, H2O; XO4+n=XO4 +XPn, n = 0, 1, 1.5, 2, 4; XP= XPMand XPA= apical anions of MH and AP cations at the periphery of the TS block.

Shkatulkalite, a Rare Mineral from the Lovozero Massif, Kola Peninsula: A Re-Investigation

“…In agreement with the suggestions by Németh et al [25] and Sokolova and Cámara [6], shkatulkalite belongs to the seidozerite supergroup, since its structure is based upon the HOH [22] or TS [17] blocks. More precisely, shatulkalite is a member of the lamprophyllite group, having Ti + (Nb + Mn) = 3 apfu, from which the H and O sheets has 2 and 1 (Ti + Nb + Mn) apfu, respectively.…”

“…[1][2][3][4][5]. Of particular interest are layered titanosilicates of the seidozerite supergroup that currently contains more than forty-five mineral species [6] with several new minerals described very recently [7][8][9][10][11][12][13]. These species occur mainly in alkaline massifs such as those in Kola Peninsula, Russia, above the Polar circle.…”

“…These species occur mainly in alkaline massifs such as those in Kola Peninsula, Russia, above the Polar circle. Belov and Organova [14] were the first who considered the crystal chemistry of several minerals of the current murmanite group of seidozerite supergroup [6]. Belov [15] and Pyatenko et al [16] made further generalizations and called minerals with a "seidozerite block" (=TS block, [17]) and astrophyllite-group minerals titanosilicate analogues of micas.…”

“…Shkatulkalite, Na 10 MnTi 3 Nb 3 (Si 2 O 7 ) 6 (OH) 2 F·12H 2 O, was described by Menshikov et al [23] from the pegmatite "Shkatulka" of the Lovozero alkaline massif, Kola Peninsula, Russia. The mineral was considered to be a Ti-Nb-sorosilicate of the "epistolite group" (now considered a part of the lamprophyllite group [24]).…”

“…The mineral was considered to be a Ti-Nb-sorosilicate of the "epistolite group" (now considered a part of the lamprophyllite group [24]). In their review on the seidozerite-supergroup minerals, Sokolova and Cámara [6] pointed out that shkatulkalite is a potential member of the supergroup, but the final assignment of the mineral to a particular group remained unclear, due to the fact that its crystal structure was unknown until now. Menshikov et al [23] established that the mineral is monoclinic, a = 5.468 (9), b = 7.18 (1), c = 31.1(1) Å, β = 94.0(2) • , V = 1218(8) Å 3 , Z = 1, and commented on the proximity of the a and b parameters of shkatulkalite to those typical for other known Ti and Nb sorosilicates.…”