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

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 Si 2 O 7 groups occur in the H sheets. The TS block is characterized by a planar minimal cell based on translation vectors, t 1 and t 2 , 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 + Fe 3+ +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, H 2 O groups and oxyanions (PO 4 ) 3- , (SO 4 ) 2- and (CO 3 ) 2- .The general formula of the TS block is as follows A P 2 B P 2 M H 2 M O 4 (Si 2 O 7 ) 2 X4+n , where M H 2 and M O 4 = cations of the H and O sheets; MH = Ti, Nb, Zr, Y, Mn, Ca + REE, Ca;MO = Ti, Zr, Nb, Fe 3+ , Fe 2+ , 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, H 2 O; X O 4 +n=X O 4 +X P n , n = 0, 1, 1.5, 2, 4; X P = X P M and X P A = apical anions of MH and AP cations at the periphery of the TS block.