question about the composition of olivine?

Question

Olivine can consist of all Mg no Fe, all Fe no Mg or an intermediate composition of part Mg and part Fe. When an imtermediate composition applies there is the ratio [Fe, Mg]: Si:O2 does this mean that there is always fixed ratio of Mg:Fe or does that part vary? In other words when there is a mixure of Mg and Fe are they always in a fixed ratio to each other?

Answer 1

Generally. That is what distinguishes it from other minerals in its class.