In close proximity to Nieder- Ofleiden is the basalt quarry at the “Hochberg”. Due to the extensive operations the opportunity results again and again to find chalcedony- filled geodes. These are similar to the so-called septarias in their structure, i.e. in their inside developed a structure of drying-clefts and -chambers, which were filled by bluish, white, more rarely greenish chalcedony.