7.1" Sea Fan-Like PSILOMELANE Branching DENDRITES on Limestone Germany for sale

The dendritic markings on this thin slab of limestone look like a fossil of a delicately branching sea fan, but this is not a fossil.  It is a natural mineralogical formation that was created when waters rich in iron and manganese infiltrated the microscopically thin space between layers of pale tan limestone and deposited the manganese mineral psilomelane. The stunning patterns on this specimen, which are colored a chocolate brown with red highlights, make this an interesting and attractive specimen of the unusual mineralogical formation called a dendrite.