Liesegang rings

As Liesegangsche rings are referred to certain recurrent structures in chemical reactions. This way, for example, when dropped from silver nitrate solution to a chromate gel at certain intervals of the Auftropfstelle red, konzentrischringförmige precipitation zones of sparingly soluble silver chromate. This phenomenon was described by Raphael Liesegang (1869-1947) in 1896 and later named after him. Besides Liesegang among others also investigated the chemist and Nobel laureate Wilhelm Ostwald (1853-1932) in this area.

Liesegangsche rings occur (sandstone) in porous and clastic rocks. The highly visible in the gate structures arise in the context of weathering by diffusion of solutions into the rock with reprecipitation in deeper areas. Brown color indicates usually indicates iron-containing compounds in the water penetrated. The structures are formed approximately parallel to the rock surface concentrically inward, but follow increasingly prescribed cracks and crevices. Known as jewelry object or noble wall paneling are the so -called " landscape stones " that have arisen on this principle.

Liesegangsche rings on the cliffs of Pénestin in Brittany

Liesegangsche rings in a sandstone with a scale ( geologist's hammer )

" Landscape Stone " from Utah