The deposit of the Halsbach coral-agate is known for a long time. It is originated 1km NNE of Halsbach. The first diggings were done before 1597. The best results in polishing this type of agate can by made by splitting the agate parallel to the vein trough the most colored layers. So you get nicely eye-agate or coral-pattern.
More informations about this locality in german