Belomarinaite, ideally KNaSO₄, is a new sulfate mineral discovered in the Toludskoe lava field, formed during the 2012–2013 Tolbachik Fissure eruption. The mineral occurs as arborescent aggregates of tabular crystals (1 mm × 0.3 mm × 0.1 mm) comprising hematite impurities. The average size of the aggregates is 0.5–0.7 mm. The empirical formula is (K_0.95Na_0.92Cu_0.04)_Σ1.91S_1.01O₄. The crystal structure of belomarinaite was determined using single-crystal X-ray diffraction data; the space group isP3m1,a= 5.6072(3),c= 7.1781(4) Å,V= 195.45(2) ų,Z= 2 andR₁= 2.6%. In the crystal structure of belomarinaite, there are six cation sites: the^[4]S1 and^[4]S2 sites are occupied by S, the^[6]Na and^[12]K sites are occupied by Na and K, respectively, giving Na_0.5K_0.5apfu and the^[10]M1 and^[10]M2 sites are occupied by Na_0.78K_0.22and K_0.78Na_0.22apfu, respectively. The crystal structure is a framework of SO₄tetrahedra, Na octahedra and K,M1 andM2 polyhedra. Belomarinaite is isostructural with the synthetic compound KNaSO₄. In belomarinaite, Na and K are disordered overM1 andM2 sites; in its synthetic analogue, Na and K are ordered overM1 andM2 sites, respectively. The Mohs’ hardness is 2–3. The mineral is uniaxial (+), with ω = 1.485(3) and ε = 1.488(3) (λ = 589 nm). The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 4.022(31)(101); 3.591(26)(002); 2.884(74)(102); 2.800(100)(110); 2.391(16)(003); 2.296(8)201; 2.008(38)(022); and 1.634(10)(212). The mineral was named in honour of Russian volcanologist Marina Gennadievna Belousova (b. 1960) for her significant contributions to the monitoring of the Tolbachik Fissure eruption.

Dobrovolskyite, Na₄Ca(SO₄)₃, is a new sulfate mineral from the Great Tolbachik fissure eruption, Kamchatka peninsula, Russia. It occurs as aggregates of tabular crystals up to 1–2 mm in maximum dimension, with abundant gas inclusions. The empirical formula calculated on the basis of O = 12 is (Na_3.90K_0.10)_Σ4(Ca_0.45Mg_0.16Cu_0.12Na_0.10)_Σ0.83S_3.08O₁₂. The crystal structure of dobrovolskyite was determined using single-crystal X-ray diffraction data as: trigonal, R3, a = 15.7223(2), c = 22.0160(5) Å, V = 4713.1(2) ų, Z = 18 and R₁ = 0.072. The Mohs’ hardness is 3.5. The mineral is uniaxial (+), with ω = 1.489(2) and ɛ = 1.491(2) (λ = 589 nm). The seven strongest lines of the powder X-ray diffraction pattern [d, Å (I, %)(hkl)] are: 11.58(40)(101); 5.79(22)(202); 4.54(18)(030); 3.86(88)(033); 3.67(32)(006); 2.855(50)(306); and 2.682(100)(330). The mineral is named in honour of Prof. Dr. Vladimir Vitalievich Dolivo-Dobrovolsky (1927–2009), one of the leading Russian scientists in the field of petrology, crystal optics and crystal chemistry. The crystal structure of dobrovolskyite can be described as composed of three symmetrically independent rods running parallel to the c axis. The rods consist of six octahedral–tetrahedral [Na(SO₄)₆]^11– or [Ca(SO₄)₆]^10– clusters of central octahedra sharing common corners with six adjacent SO₄ tetrahedra. Alternatively, the crystal structure of the mineral can be described as a 12-layer ABACABACABAC eutactic array of Na⁺ and Ca²⁺ cations, and vacancies with disordered (SO₄) tetrahedra in interstices. Dobrovolskyite and similar minerals probably formed upon cooling of a high-temperature phase with disordered cation and anion arrangements.