Olivenite-Adamite Solid Solution From Oxidation Zone in Rędziny (West Sudetes, Poland)

An extensive hydrothermal polymetallic mineralization with a well developed oxidation zone rich in secondary minerals occurs in dolostones several hundred meters from the Karkonosze granite at Rędziny. Using XRD and FTIR methods, mineral phases representing transitional members of the olivenite-adamite solid solution have been identified. Electron microprobe analyses reveal the most common varieties to be zincian olivenite and cuprous adamite with compositions ranging from (Cu_1.17Zn_0.83)(AsO₄)(OH) to (Zn_1.38Cu_0.62)(AsO₄)(OH). The two minerals are subordinate in the weathering zone which can be characterized as having been a zone of low Cu²⁺ and Zn²⁺ activity and with mineralizing solutions of increased pH. A high Ca²⁺ concentration due to the ubiquitous presence of carbonate rocks resulted in the expansion of the stability field of another arsenate, conichalcite (or Zn-bearing conichalcite), which is a common mineral there.