Fe in P-doped basaltic melts: A Mössbauer spectroscopy study

•The addition of P to a ferrobasalt causes a structural collapse.•At low contents, P enters the glass structure as a network former.•At high contents, P causes a structural collapse linked to a phase separation.•A disordered nano-oxide and stanfieldite increase melt’s viscosity.•The Mössbauer parameters of stanfieldite are similar to those of the alluaudite group.