Publication Date:
2019
Description:
〈div data-abstract-type="normal"〉〈p〉Belomarinaite, ideally KNaSO〈span〉4〈/span〉, 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〈span〉0.95〈/span〉Na〈span〉0.92〈/span〉Cu〈span〉0.04〈/span〉)〈span〉Σ1.91〈/span〉S〈span〉1.01〈/span〉O〈span〉4〈/span〉. The crystal structure of belomarinaite was determined using single-crystal X-ray diffraction data; the space group is 〈span〉P〈/span〉3〈span〉m〈/span〉1, 〈span〉a〈/span〉 = 5.6072(3), 〈span〉c〈/span〉 = 7.1781(4) Å, 〈span〉V〈/span〉 = 195.45(2) Å〈span〉3〈/span〉, 〈span〉Z〈/span〉 = 2 and 〈span〉R〈/span〉〈span〉1〈/span〉 = 2.6%. In the crystal structure of belomarinaite, there are six cation sites: the 〈span〉[4]〈/span〉〈span〉S〈/span〉1 and 〈span〉[4]〈/span〉〈span〉S〈/span〉2 sites are occupied by S, the 〈span〉[6]〈/span〉Na and 〈span〉[12]〈/span〉K sites are occupied by Na and K, respectively, giving Na〈span〉0.5〈/span〉K〈span〉0.5〈/span〉 apfu and the 〈span〉[10]〈/span〉〈span〉M〈/span〉1 and 〈span〉[10]〈/span〉〈span〉M〈/span〉2 sites are occupied by Na〈span〉0.78〈/span〉K〈span〉0.22〈/span〉 and K〈span〉0.78〈/span〉Na〈span〉0.22〈/span〉 apfu, respectively. The crystal structure is a framework of SO〈span〉4〈/span〉 tetrahedra, Na octahedra and K, 〈span〉M〈/span〉1 and 〈span〉M〈/span〉2 polyhedra. Belomarinaite is isostructural with the synthetic compound KNaSO〈span〉4〈/span〉. In belomarinaite, Na and K are disordered over 〈span〉M〈/span〉1 and 〈span〉M〈/span〉2 sites; in its synthetic analogue, Na and K are ordered over 〈span〉M〈/span〉1 and 〈span〉M〈/span〉2 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 [〈span〉d〈/span〉, Å (〈span〉I〈/span〉, %) (〈span〉hkl〈/span〉)] 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.〈/p〉〈/div〉
Print ISSN:
0026-461X
Electronic ISSN:
1471-8022
Topics:
Geosciences
Permalink