OXIDES
The oxide minerals all contain one or more oxide
anions (O-2). The oxide minerals include species that are
hydroxy-oxides. The hydroxide minerals (those with one or more OH-)
are usually considered together with the oxides. Many sulfide minerals
are not stable in Earth-surface conditions. In the presence of oxygen and
moisture, sulfide minerals tend to tarnish or alter to oxides and
hydroxy-oxides. All except the most inert elements (such as the
platinum-group elements and gold and noble gases) readily form oxides.
Gold oxide forms only under special conditions.
Franklinite
((Zn,Fe,Mn)(Fe,Mn)2O4)
Romanechite (BaMn+2Mn+48O16(OH)4)