Incongruent melting
Incongruent melting occurs when a solid substance being
silica (SiO2). The proportions of leucite and melt formed can be recombined to yield the bulk composition of the starting feldspar. Another mineral that can melt incongruently is enstatite (Mg2Si2O6), which produces forsterite (Mg2SiO4) in addition to a melt richer in SiO2 when melting at low pressure. Enstatite melts congruently at higher pressures between 2.5 and 5.5 kilobars
.
See also
References
- Incongruent melting from Eric Weisstein's World of Physics