Besides Ca carbonate, pyrite, and marcasite also various other minerals in the museum's collections are threatened by depreciation and destruction. Thus, e.g., light affects the fading of pink quartz or the darkening of proustite and pyrargyrite. The latter two minerals in time disintegrate into a powdery matter by the effect of weathering. Cut metallic meteorites merit, of course, a special attention as their mirror-like polished section surface is highly sensitive even to a mere touch of a human hand. In the very spot soon an imprint appears made up of rust from the action of traces of Na chloride present in the sweat. Thus, it is necessary to carry out the conservation of the meteorites as soon as possible after their grinding and etching with acid.