A study of the rate of gypsum leaching from the pore space of sandstones

Experimental studies of the rate of gypsum leaching from the pore space in sandstone revealed a zone with higher dolomite content (due to dolomitization of calcite in the peripheral region of the block), with minimum values of gypsum content and maximum ones of total porosity. It is shown that leaching from rock blocks in the near-shore zone of the Kafirnigan (Kofarnihon) River is defined by two successive stages: (1) leaching of the dolomitization zone (the slowest) and (2) from the field with background values of dolomite and calcite (fast). The average value of the coefficient of diffusion for Ca²⁺ ions in the second region is higher by ~70% than in the first one.