The study examines the content of heavy metals like iron and copper in lichens from the Acarosporetum sinopicae association, found on medieval mining slag heaps in the Harz region. Due to the toxic nature of these substrates, typical vegetation is sparse, but specialized lichen species thrive in such environments. The research investigates the specific ability of these lichens to accumulate and tolerate heavy metals, with quantitative analyses revealing high concentrations of iron and copper in their thalli. The mechanisms of metal uptake, including histochemical localization and distribution in the thallus, are discussed, highlighting adaptive traits for metal tolerance. The findings contribute to understanding ecological specialization and environmental adaptation among lichens. Lichens, heavy metals, iron, copper, Acarosporetum sinopicae, slag heaps, environmental adaptation, Harz region