Rare oxide-sulfosilicate-sulfate mineral assemblages have been identified in burned material from two spoil heaps (Kukla mine, Oslavany, and Ferdinand mine, Zastávka) in the Rosice-Oslavany coalfield, Czech Republic. The assemblages are deficient in Si and Al, and contain high amounts of fluorine and chlorine; major minerals are gypsum, anhydrite, fluorellestadite, periclase, brucite, and portlandite. Accessory minerals include magnesioferrite, Mn-rich srebrodolskite, and rare kumtyubeite, Fe,Cl-rich brearleyite/mayenite, wadalite, fluorite, cuspidine, rondorfite, and an unnamed mineral with composition Ca4(Mn,Fe)2O7. The assemblages are pyrometamorphic products of a dolomite-anhydrite-gypsum protolith, at Tmin > 800 °C. The most probable source of halogens was organic matter.