Dritsite, Li2Al4(OH)12Cl2·3H2O, a New Gibbsite-Based Hydrotalcite Supergroup Mineral

Abstract

Dritsite, ideally Li2Al4(OH)12Cl2·3H2O, is a new hydrotalcite supergroup mineral formed as a result of diagenesis in the halite−carnallite rock of the Verkhnekamskoe salt deposit, Perm Krai, Russia. Dritsite forms single lamellar or tabular hexagonal crystals up to 0.25 mm across. The mineral is transparent and colourless, with perfect cleavage on {001}. The chemical composition of dritsite (wt. %; by combination of electron microprobe and ICP−MS; H2O calculated by structure refinement) is: Li2O 6.6, Al2O3 45.42, SiO2 0.11, Cl 14.33, SO3 0.21, H2Ocalc. 34.86, O = Cl − 3.24, total 98.29. The empirical formula based on Li + Al + Si = 6 apfu (atom per formula unit) is Li1.99Al4.00Si0.01[(OH)12.19Cl1.82(SO4)0.01]Σ14.02·2.60(H2O). The Raman spectroscopic data indicate the presence of O–H bonding in the mineral, whereas CO32– groups are absent. The crystal structure has been refined in the space group P63/mcm, a = 5.0960(3), c = 15.3578(13) Å, and V = 345.4(5) Å3, to R1 = 0.088 using single-crystal data. The strongest lines of the powder X-ray diffraction pattern (d, Å (I, %) (hkl)) are: 7.68 (100) (002), 4.422 (61) (010), 3.832 (99) (004, 012), 2.561 (30) (006), 2.283 (25) (113), and 1.445 (26) (032). Dritsite was found as 2H polytype, which is isotypic with synthetic material and shows strong similarity to chlormagalumite-2H. The mineral is named in honour of the Russian crystallographer and mineralogist Prof. Victor Anatol`evich Drits.

Krasnoshteinite, Al8[B2O4(OH)2](OH)16Cl4⋅7H2O, a New Microporous Mineral with a Novel Type of Borate Polyanion

“…These groups are connected with clusters of Al-centered octahedra via common vertices. Thus, a BO 3 triangle shares one O vertex with a B-centered tetrahedron, one vertex with two Al-centered octahedra [Al(4) and Al (7)] of the layer, and one vertex with Al(1)-and Al(2)-centered octahedra of an adjacent layer (thus reinforcing the linkage between neighboring octahedral layers). A BO 2 (OH) 2 tetrahedron shares one O vertex with a BO 3 triangle, one O vertex with two Al-centered octahedra [Al(3) and Al(4)], and one O=OH vertex with a Al(5)-centered octahedron; all Al (3,4,5) octahedra belong to the same layer.…”

“…It is based upon the (010) corrugated layers of Al-centered octahedra connected via common vertices to form a pseudo-framework. There are eight crystallographically non-equivalent octahedrally coordinated Al sites: Al(1) and Al (7) cations center octahedra AlO(OH) 4 (OH 2 ), Al(2,3) -AlO(OH) 5 , Al(4) -AlO 2 (OH) 4 , Al(5) -Al(OH) 5 (OH 2 ), Al(6) -Al(OH) 6 , and Al(8) -Al(OH) 4 (OH 2 ) 2 . These Al-centered octahedra play different structural roles.…”

“…Huge deposits are given in monographs [5,6]. Krasnoshteinite occurs in halite-carnallite rock and is associated with dritsite (Li 2 Al 4 (OH) 12 Cl 2 ·3H 2 O) [7], dolomite, magnesite, quartz, Sr-bearing baryte, kaolinite, potassic feldspar, congolite, members of the goyazite SrAl 3 (PO 4 )(PO 3 OH)(OH) 6 -woodhouseite CaAl 3 (PO 4 )(SO 4 )(OH) 6 series, fluorite, hematite, and anatase. The new mineral was probably formed as a result of diagenetic or post-diagenetic processes in halite-carnallite evaporitic rock of the Layer E of the Verkhnekamskoe deposit.…”

Akopovaite, Li2Al4(OH)12(CO3)(H2O)3, a new Li member of the hydrotalcite supergroup from Turkestan Range, Kyrgyzstan

“…5. The band assignment is provided in Table 3 and compared with its synthetic analogue (Drewien et al ., 1996), dritsite (Zhitova et al ., 2019a) and quintinite (Theiss et al ., 2015). The Raman spectrum reveals the presence of carbonate groups and different OH vibrations that correspond to hydroxyl and interlayer water (Table 3).…”

“…(CO 3 ) 2– , (OH) – , Cl – , (SO 4 ) 2– and (Sb(OH) 6 ) – ] and water molecules. Natural [dritsite (Zhitova et al ., 2019a) and akopovaite (reference therein)] and synthetic LiAl 2 -members (see references for synthetic analogue of akopovaite and related LDHs in Table 1) are structurally based on gibbsite layers, whereas all the other LDHs are composed of divalent and trivalent cations and brucite-type layers. The characterisation of akopovaite was facilitated by the previously described synthetic analogue of akopovaite and related LDHs (Devyatkina et al ., 1983; Drewien et al ., 1996; Isupov, 1999; Isupov et al ., 2007; Serna et al ., 1977, 1982; Table 1).…”