Directions:

The Goslar-Oker region is important because of the history of zinc production and the source of cadmium (an impurity in zinc), which was discovered in Göttingen (see below); and because selenium-bearing ores from Tilkerode (see below) were smelted here, which served as a source for thallium, discovered by Crookes in London {LINK to London}.
RR Station, Bahnhofsvorplatz - N51 54.66 E10 25.36.
Rammelsberg Erzbergwerk, excellent museum not only on silver production, but of interest to "Rediscovery" explorers, on zinc production and cadmium impurities, Rammelsberger Straße - N51 53.39 E10 25.09.
Harzmetall GmbH, a company associated with the original lead smelting industry; historical equipment remains as well as the ruins of an old smelter; this is possibly the very smelter that yielded thallium-rich sludge that Crookes analyzed; Hüttenstraße 6, Oker - N51 54.05 E10 29.09.