Definition of posnjakite in English:

posnjakite

Pronunciation /ˈpɒznjəkʌɪt/

noun

Mineralogy
  • A rare blue to greenish-blue mineral, occurring in encrustations and prismatic crystals, which is a hydrated basic copper sulphate, Cu₄ (SO₄)(OH)₆ ·H₂ O, closely similar to langite and crystallizing in the monoclinic system.

Origin

1960s; earliest use found in Mineralogical Abstracts. From the name of Eugene Waldemar Posnjak, U.S. geochemist + -ite, after Russian poznjakit.