The coordination number of ferrous ions in silicate glasses

Mössbauer and optical absorption measurements on a number of silicate glasses show that most of the ferrous ions in these glasses are distributed over two types of octahedral sites. Less than 0.5% of all ferrous ions occupy tetrahedral sites. It is shown that the Bernal liquid model of random close packing does not apply to silicate glasses. Attention is drawn to the fact that measurements on silicate glasses cannot provide reliable information about coordination numbers in silicate liquids.