TY - JOUR

T1 - Kalithallite, K3Tl3+Cl6 2H2O, a new mineral with trivalent thallium from the Tolbachik volcano, Kamchatka, Russia

AU - Pekov, Igor V.

AU - Krzhizhanovskaya, Maria G.

AU - Yapaskurt, Vasiliy O.

AU - Belakovskiy, Dmitry I.

AU - Sidorov, Evgeny G.

AU - Zhegunov, Pavel S.

PY - 2023/4/1

Y1 - 2023/4/1

N2 - A new mineral kalithallite, K 3 Tl 3+ Cl 6 ⋅2H 2 O, was found in an active fumarole belonging to the Northern fumarole field at the First scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. Kalithallite is a product of the relatively low-temperature (70–150°C) interactions involving high-temperature sublimate minerals, volcanic gas and atmospheric water vapour. The associated minerals are cryobostryxite, KZnCl 3 ⋅2H 2 O, halite, sylvite, opal and gypsum. Kalithallite forms lamellar to tabular crystals up to 5 × 30 × 40 μm combined in open-work aggregates up to 1 mm across. It is transparent, colourless in individuals and white to pale cream coloured or pale beige in aggregates, with vitreous lustre. D calc = 3.01 g cm –3 . Kalithallite is optically uniaxial (–), ɛ = 1.656(3) and ω = 1.662(3). The chemical composition (wt.%, electron-microprobe data, H 2 O calculated by stoichiometry) is: K 17.72, Zn 0.85, Tl 38.76, Cl 35.91, H 2 O calc 5.99, total 99.23. The empirical formula calculated on the basis of K+Zn+Tl+Cl = 10 apfu is K 2.72 Zn 0.06 Tl 1.14 Cl 6.08 ⋅2H 2 O. Kalithallite is tetragonal, I 4/ mmm , a = 15.9333(5), c = 18.1088(7) Å, V = 4595.2(4) Å 3 and Z = 14. The strongest reflections of the powder X-ray diffraction (XRD) pattern [ d ,Å( I )( hkl )] are: 5.98(100)(202); 5.64(36)(220); 3.984(20)(400); 3.528(30)(224); 3.315(22)(422); 2.890(15)(334); and 2.817(24)(206, 440). Kalithallite is isotypical to synthetic K 3 Tl 3+ Cl 6 ⋅2H 2 O. The crystal structure was refined from the powder XRD data using the Rietveld method, R Bragg = 0.55%, R p = 0.56%, and R wp = 0.75%. The structure contains Tl 3+ Cl 6 octahedra and K-centred polyhedra of three types: KCl 8 , KCl 8 (H 2 O) and KCl 7 (H 2 O) 2 . The mineral is named as a kali um– thall ium ordered compound.

AB - A new mineral kalithallite, K 3 Tl 3+ Cl 6 ⋅2H 2 O, was found in an active fumarole belonging to the Northern fumarole field at the First scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. Kalithallite is a product of the relatively low-temperature (70–150°C) interactions involving high-temperature sublimate minerals, volcanic gas and atmospheric water vapour. The associated minerals are cryobostryxite, KZnCl 3 ⋅2H 2 O, halite, sylvite, opal and gypsum. Kalithallite forms lamellar to tabular crystals up to 5 × 30 × 40 μm combined in open-work aggregates up to 1 mm across. It is transparent, colourless in individuals and white to pale cream coloured or pale beige in aggregates, with vitreous lustre. D calc = 3.01 g cm –3 . Kalithallite is optically uniaxial (–), ɛ = 1.656(3) and ω = 1.662(3). The chemical composition (wt.%, electron-microprobe data, H 2 O calculated by stoichiometry) is: K 17.72, Zn 0.85, Tl 38.76, Cl 35.91, H 2 O calc 5.99, total 99.23. The empirical formula calculated on the basis of K+Zn+Tl+Cl = 10 apfu is K 2.72 Zn 0.06 Tl 1.14 Cl 6.08 ⋅2H 2 O. Kalithallite is tetragonal, I 4/ mmm , a = 15.9333(5), c = 18.1088(7) Å, V = 4595.2(4) Å 3 and Z = 14. The strongest reflections of the powder X-ray diffraction (XRD) pattern [ d ,Å( I )( hkl )] are: 5.98(100)(202); 5.64(36)(220); 3.984(20)(400); 3.528(30)(224); 3.315(22)(422); 2.890(15)(334); and 2.817(24)(206, 440). Kalithallite is isotypical to synthetic K 3 Tl 3+ Cl 6 ⋅2H 2 O. The crystal structure was refined from the powder XRD data using the Rietveld method, R Bragg = 0.55%, R p = 0.56%, and R wp = 0.75%. The structure contains Tl 3+ Cl 6 octahedra and K-centred polyhedra of three types: KCl 8 , KCl 8 (H 2 O) and KCl 7 (H 2 O) 2 . The mineral is named as a kali um– thall ium ordered compound.

UR - https://www.mendeley.com/catalogue/256b9135-9457-3000-927f-24600334d52a/

U2 - 10.1180/mgm.2022.124

DO - 10.1180/mgm.2022.124

M3 - Article

VL - 87

SP - 186

EP - 193

JO - Mineralogical Magazine

JF - Mineralogical Magazine

SN - 0026-461X

IS - 2

ER -