The Origin of the Moon (1986) gives an estimate of the total average composition of the Moon. Let's consider for this problem that this composition is a good estimate of what exists in the Moon's interior where the partial melting we are interested in occurred. The concentration of Iron oxide (FeO) reported in Origin of the Moon is 13%, meaning that 13 percent of the Moon is Iron oxide (FeO). The rest of it is other chemical components, such as Silicon dioxide (SiO₂), Aluminum oxide (Al ₂O₃), Magnesium oxide (MgO), Calcium oxide (CaO), Sodium oxide (Na₂O).