Wiktionary
posnjakite
n. (context mineralogy English) A particular mineral containing copper, sulphur, hydrogen, and oxygen.
Wikipedia
Posnjakite
Posnjakite is a hydrated copper sulfate mineral. It was discovered in the Tungsten deposit of Nura-Taldy in Karaganda Region in Kazakhstan and described in 1967 by Aleksandr Ivanovich Komkov (1926–1987) and Yevgenii Ivanovich Nefedov (1910–1976) and named after geochemist Eugene Valdemar Posnjak (1888–1949).