Specimens of fettelite, a complex silver-mercury sulfoarsenide, are very rare and even less so at this size. Under magnification we can observe burgundy red laminar crystals of fettelite, together with idiomorphic crystals of proustite. An exceptional piece.

Rübenkeller is the famous historical locality for chabazite and phillipsite from about 1850 and was very prolific in zeolite specimens in the late 19th century. In this specimen, from the Freiburg Bergakademie, we can see various aggregates of very well defined, pseudocubic, transparent and very bright crystals, which fill the vacuoles of the volcanic rock. It is accompanied by a very interesting old handwritten label.

Deep red eleonorite crystal aggregates with some delvauxite on limonite. Classic sample from Rotläufchen mine near Waldgirmes, Hesse, type locality for the species. Closely related to beraunite and forms by oxidation of the latter.

Vug in basaltic matrix lined with extremely fine acicular crystals of mesolite. From a German locality not well represented in collections.