Mineral And Chemical Composition Of Selected Clinoptilolite Tuffs And Migration Of Elements In Acidic Aqueous Media

The two studied samples of Bulgarian zeolitized tuffs (one sold as zeolite supplement and another from the Most deposit quarry) contain clinoptilolite (70-80%), plagioclase, sanidine, opal-CT, mica, quartz, and accessory minerals (apatite, monazite, montmorillonite). A total of 62 element contents were determined in the tuffs, as Se, Cd, Bi, U, Cs, Pb, Ag, Rb, Tl, Sn, Th, In, Sb, W, and K have elevated contents compared to upper continental crust. The samples are characterized by low contents of the critical rare earth elements. The migration of 24 elements from clinoptilolite tuffs was determined in aqueous acidic media. The contents of migrated elements in the ultrapure water leachates are lower than the maximum permissible levels for drinking water. The zeolite supplement treated with 0.02% HCl aqueous solution shows greater migration of elements and higher concentrations. Some of these elements are toxic or potentially toxic in high concentrations - Al, Mn, P, and others.