Vote for your favorite mineral in #MinCup26! - Sphalerite vs. Anorthite Both zinc ore Sphalerite and calcium plagioclase feldspar Anorthite have perfect cleavage that will split cleanly if you hit them with a hammer, but only one can claim a larger split of your votes!
Beraunite was originally defined as a fully oxidised mineral, but was redefined by Fanfani and Zanazzi (1967), on the basis of a crystal structural analysis, as a mixed-valence iron phosphate and they left the original fully oxidized end-member unnamed. In essence, Fanfani and Zanazzi (1967) had discovered a new mineral species (ferroberaunite) but re-used a previous name. In the 19th century, both beraunite and eleonorite had been applied to the fully oxidized mineral. Eleonorite had been re-applied by the IMA to the oxidized end-member of the beraunite-eleonorite series. In the IMA 21-D redefinition the name beraunite was reapplied to the oxidised phase and the name ferroberaunite was created for the mixed-valence phase (Tvrdy et al., 2021).
