New data on celestine-rich salts in the Wieliczka salt deposits

Abstract

Pale brownish celestine-rich salt rocks were found near the Franciuszek Müller gallery, in the chambers of the 3rd level in the Wieliczka Salt Mine. The complex of rock salts subjected to exploration occurred within a large seam approximately 15 m thick. Detailed research revealed that the salt has the form of a block incorporated within the gray salts body and being similar to other blocks of green salts, well known in the upper part of the deposit. A characteristic petrographical feature of the pale brown rock salt owed to the presence of celestine ($SrSO_{4}$). That strontium mineral was re-examined, using X-ray powder data, and scanning microscope observations, with EDS analysis. The investigated rock salts exhibited a mineral association of halite (main component), anhydrite, celestine, calcite, gypsum, clay materials, iron compounds and a small amount of bitumen. Interrigenous sediments and the insoluble part of salt occurred higher content of strontium that in halite. Celestine crystals were observed in two forms: elongated platy crystals, forming fan-shaped aggregates and granular aggregates, strongly associated with anhydrite. On carbonate and sulphate strontium usually appearing as needle shaped aggregates of celestine. No barium minerals were observed. The development and paragenesis of celestine suggested a post-sedimentary origin of these rocks that ought to be connected with diagenetic processes. An important observation that confirmed that thesis was the transformation of fine crystalline anhydrite into platy crystals, recrystallization and primary accumulation of strontium, as a result of evaporation processes.