Chromceladonite from the Southern Sarany Chromite Deposit (Northern Urals)

Resumo

Abstract—Chromceladonite in chromitites of the Southern Sarany chromium deposit (the Urals) occurs in two mineral associations: as crusts of acicular grains on uvarovite crystals and in thin-scale aggregates together with quartz and chlorite in brecciated zones developed after chromitites. The chemical composition of chromceladonite (wt %) is K₂O 9.4, MgO 6.8, Cr₂O₃ 17.1, SiO₂ 51.7, Al₂O₃ 8.5, CaO 0.1, FeO 0.2, H₂O⁺ 5.7. The sum is 99.7. Empirical formula: K_0.82(Cr_0.93Mg_0.70 ⋅ Al_0.25Ti_0.05Fe_0.01)_Σ1.94[(Si_3.56Al_0.44)_Σ4.00(O_9.39OH_0.61)_Σ10(OH)₂. Parameters of an elementary sell: a = 5.271(5), b = 9.015(6), c = 10.171(7) Å, β = 101.82(8)°, V = 475(1) ų. The formation temperature of celadonite is as high as 300°C. A source of potassium for chromceladonite can be both country black shales and phlogopite-bearing rocks of the Southern Sarany massif.