“… The place of discovery Geroldsau - Klösterle is famous for the extremely beautiful, radiated pseudomorphous agates in red colouring. The agates are situated quite near the surface. Unfortunately they are weathered however in such a way that very rarely a whole thunderegg is to be found. Originally it must have concerned partially quite large thundereggs, which are to be found however only as fragments. Geroldsau lies in the range of the boundary Baden-Baden, so that looking for of agates is not permitted in the city forest….”

written by Patricia Hemmer, in “thundereggs from the Black Forest” - catalog to the international agate-fair 2012