Chromceladonite from the Southern Sarany Chromite Deposit (Northern Urals)

—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 K 2 O 9.4, MgO 6.8, Cr 2 O 3 17.1, SiO 2 51.7, Al 2 O 3 8.5, CaO 0.1, FeO 0.2, H 2 O + 5.7. The sum is 99.7. Empirical formula: K 0.82 (Cr 0.93 Mg 0.70 ⋅ Al 0.25 Ti 0.05 Fe 0.01 ) Σ1.94 [(Si 3.56 Al 0.44 ) Σ4.00 (O 9.39 OH 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) Å 3 . 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.