The small Freisbach - River is running through the Freisen Valley. It is transporting gravel and agate-pebbles from a lot of famous agate-finding-locations around Freisen to the west. On the fields around Asweiler agate-collectors do have the possibility to find agate-specimen from these localities.
Typical for the agate-finding-location “Heiliger Brunnen” are so called “Membrantrümmer-agates” and orange-coloured agates, for the location “auf Hassel” cloud-agates, for the location “Freisener Höhe” intensively yellow coloured Iron-Jasper and for the “Heide-Gemeinden” (Hahnweiler and Rückweiler) water-level-structures.
Very interesting for the collectors are star-quartz-formations or mossy-agate-structures from the fields of Asweiler. The primarly location of these types of agate is still unknown.