Original paper

Hydrothermal fluorite-forming processes in the Mikhalkovo deposit (Central Rhodopes, Bulgaria) field observation and experimental confirmation

Zidarova, Bogdana


A reconstruction of the fluorite formation in the Mikhalkovo deposit (Central Rhodopes, Bulgaria) has been made. The deposit is of strata-bound type and the mineralization is located in marble beds according to two mechanisms, metasomatic and secretional. A system approach is applied to the field and experimental studies. The theoretical and observed morphology of the crystals, their spatial distribution in the deposit, as well as the sequence of formation of crystal forms are discussed. Experiments have been made for to explain each of the mineral forming processes, and namely, diffusion in solutions and gels, and diffusion metasomatism of marbles, for the metasomatic process, and dissolution, synthesis and growth in hydrothermal conditions, gravitational, density and chemical differentiation of the solutions, for the secretional one. The results obtained about the determination of the thermal transfer in the different parts of the region of the deposit, the composition and pH of the fluid inclusions and the composition of the contemporary underground waters allow a reconstruction of the paleorelief. The mineral products from the interaction of the hydrothermal solutions with the host rocks indicate the source of NaF and Na2SiF6 for realization of the different mechanisms of fluorite formation. The obtained result may be used for prognosis of the richest parts in the deposits, searching of new perspective parts and controlling the width of the mineralized interval in the horizontal sections of the ore bodies.


fluoriteexperimental modelingdiffusionhydrothermal processmetasomatismmorphology and crystal morphology evolutionthermal regimecomposition of solutionsprognostic criteria